javascript get current function name in strict mode

* isn't going to help. are deprecated, SyntaxError: "use strict" not allowed in function with non-simple parameters, SyntaxError: "x" is a reserved identifier, SyntaxError: a declaration in the head of a for-of loop can't have an initializer, SyntaxError: applying the 'delete' operator to an unqualified name is deprecated, SyntaxError: await is only valid in async functions, async generators and modules, SyntaxError: cannot use `? By clicking Post Your Answer, you agree to our terms of service, privacy policy and cookie policy. In sloppy mode, a number beginning with a 0, such as 0644, is interpreted as an octal number (0644 === 420), if all digits are smaller than 8. arguments.callee will give you a reference to the calling function, not a function name in string. The concatenation of strict mode scripts with each other is fine, and concatenation of non-strict mode scripts is fine. arguments.callee unfortunatelly deprecated, and using it throws an error in "strict mode". "use strict" is just a string, so IE 9 will not throw an error even if it does not understand it. The guides section is new and still under construction. All browser compatibility updates at a glance, Frequently asked questions about MDN Plus. var functionName = function() {} vs function functionName() {}. Those s*****s are not happy enough complexing their stuff, they have to limit other's software. SyntaxError: Unexpected '#' used outside of class body, SyntaxError: unlabeled break must be inside loop or switch, SyntaxError: unparenthesized unary expression can't appear on the left-hand side of '**', SyntaxError: Using //@ to indicate sourceURL pragmas is deprecated. Example: strict mode. 565), Improving the copy in the close modal and post notices - 2023 edition, New blog post from our CEO Prashanth: Community is the future of AI. How to get the children of the $(this) selector? All these attempts to do so are syntax errors: Strict mode code doesn't sync indices of the arguments object with each parameter binding. Asking for help, clarification, or responding to other answers. You need something like this if you want the arguments of MyFunction(): You can't do better than reliably, since that function has almost nothing to do with the error handler: The error handler can very possibly have been created in another context entirely, one enclosing MyFunction, or passed into it etc. These differences are very subtle differences. Browse other questions tagged, Where developers & technologists share private knowledge with coworkers, Reach developers & technologists worldwide, I must be missing something. it's read-only) throws a, Deleting a non-deletable property throws a. Console.trace is too verbose and will produce multiple lines, when I need only function name. Browse other questions tagged, Where developers & technologists share private knowledge with coworkers, Reach developers & technologists worldwide, @Nick: Oh, I know that JScript 5.5 does not implement Javascript 1.5. Browsers not supporting strict mode will run strict mode code with different behavior from browsers that do, so don't rely on strict mode without feature-testing for support for the relevant aspects of strict mode. Copy and paste console.debug (arguments.callee) is more convenient ( I do not need to repeat function name). stackman - npm Package Health Analysis | Snyk It is not a statement, but a literal expression, ignored by earlier versions Strict mode makes it easier to write "secure" JavaScript. or a function. How to change the background color after clicking the button in JavaScript . How a top-ranked engineering school reimagined CS curriculum (Ep. JavaScript SyntaxError - "use strict" not allowed in function with non-simple parameters, Strict Inequality(!==) Comparison Operator in JavaScript, Strict Equality(===) Comparison Operator in JavaScript. Why do you need the function name? In sloppy mode, modifying a value in the arguments object modifies the corresponding named argument. Why typically people don't use biases in attention mechanism? Was Stephen Hawking's explanation of Hawking Radiation in "A Brief History of Time" not entirely accurate? In ES5 and above, there is no access to that information. A simple solution to dynamically retrieve function names [like magic variables] is the use of scoped variables, and the Function.name property. Given a function and the task is to get the name of function that is currently running using JavaScript. acknowledge that you have read and understood our, Data Structure & Algorithm Classes (Live), Data Structures & Algorithms in JavaScript, Data Structure & Algorithm-Self Paced(C++/JAVA), Full Stack Development with React & Node JS(Live), Android App Development with Kotlin(Live), Python Backend Development with Django(Live), DevOps Engineering - Planning to Production, GATE CS Original Papers and Official Keys, ISRO CS Original Papers and Official Keys, ISRO CS Syllabus for Scientist/Engineer Exam, Inline HTML Helper HTML Helpers in ASP.NET MVC, Different Types of HTML Helpers in ASP.NET MVC. How can I add new array elements at the beginning of an array in JavaScript? By using our site, you JavaScript sometimes makes this basic mapping of name to variable definition in the code impossible to perform until runtime. Strict Mode was a new feature in ECMAScript 5 that allows you to place a program, or a function, in a strict operating context. How to find all inputs that don't have color name and appends text to the span next to it using jQuery ? Find centralized, trusted content and collaborate around the technologies you use most. Instantly share code, notes, and snippets. JavaScript's flexibility makes it effectively impossible to do this without many runtime checks. Source: Javascript - get current function name. It can be applied to individual functions. , so the answer from @Sayem is only valid if you aren't using strict mode. JavaScript was designed to be easy for novice developers, and sometimes it gives operations which should be errors non-error semantics. Which one to choose? You could convert your function into a string (fn + '') and split it later at whitespace and open bracket /\s|\(/. Thus for a strict mode function, the specified this is not boxed into an object, and if unspecified, this is undefined instead of globalThis: In strict mode it's no longer possible to "walk" the JavaScript stack. You cannot deprecate/obsolete/kill that which is actively used all over the web. How? How to execute a JavaScript function when I have its name as a string. Also, we can enable strict mode for some specific functions too, which will enable strict mode for only . A few strict mode tweaks, plus requiring that user-submitted JavaScript be strict mode code and that it be invoked in a certain manner, substantially reduce the need for those runtime checks. That way I can shown an error and know in which function the error happened without hardcoding the function's name, get the current function name in javascript. Find centralized, trusted content and collaborate around the technologies you use most. Why typically people don't use biases in attention mechanism? How can I add multiple sources to an HTML5 audio tag, programmatically? To learn more, see our tips on writing great answers. Which ability is most related to insanity: Wisdom, Charisma, Constitution, or Intelligence? You can only get the name of a function you have a reference to, and you cannot get a reference to an arbitrary function in the call stack. So for other coming here the answer is YES and you can just add this line: Moment.js | Guides This syntax has a flow, it isnt possible to blindly concatenate non-conflicting scripts. webpack: Module not found: Error: Cant resolve (with relative path). If it's dynamic, you're already accessing it by name, or no? Visit Mozilla Corporations not-for-profit parent, the Mozilla Foundation.Portions of this content are 19982023 by individual mozilla.org contributors. For a sloppy mode function, this is always an object: either the provided object, if called with an object-valued this; or the boxed value of this, if called with a primitive as this; or the global object, if called with undefined or null as this. JavaScript used to silently fail in contexts where what was done should be an error. Why not just write. Strict mode fixes mistakes that make it difficult for JavaScript engines to perform optimizations: strict mode code can sometimes be made to run faster than identical code thats not strict mode. Introductory Concepts. It's surprising nobody else has pointed that out in the almost 3 years this answer has been here :-). object, will throw an error. are not allow to access their receiver and function objects. Get current function name in strict mode I need the current function name as a string to log to our log facility. How to Open URL in New Tab using JavaScript ? By clicking Accept all cookies, you agree Stack Exchange can store cookies on your device and disclose information in accordance with our Cookie Policy. Be aware that this feature may cease to work at any time. Actually, actually paying more attention to your question, it sounds like you might want the extra junk :), This worked for me but I think there's a typo in your regexp. In sloppy mode, arguments.callee refers to the enclosing function. JavaScript in browsers can access the user's private information, so such JavaScript must be partially transformed before it is run, to censor access to forbidden functionality. Note: Sometimes you'll see the default, non-strict mode referred to as sloppy mode. You may have to parse the name though, as it will probably include some extra junk. In strict mode, the value is passed directly without conversion or replacement. How to jQuery : Can I get the name of the currently running function in JavaScript? Reconstructing the stack and recursion Note that in case of recursion, you can't reconstruct the call stack using this property. How to convert a sequence of integers into a monomial. For those frames, getFunction() will return undefined. Also, this technique cannot work with anonymous functions. Hack or not, that's still the best I know of. Note that format of the string returned by Error.prototype.stack is implemented differently in different engines, so this probably won't work everywhere: About other solutions: arguments.callee is not allowed in strict mode and Function.prototype.calleris non-standard and not allowed in strict mode. As noted this applies only if your script uses "strict mode". Difference between var and let in JavaScript, Convert a string to an integer in JavaScript. The property of ampere const object can be changed but e cannot shall changed to ampere reference on to recent object Examples might be simplified to improve reading and learning. The execution context is not the global object anymore, contrary to above case 2.1. Implicit binding covers most of the use-cases for dealing with the this keyword. Site design / logo 2023 Stack Exchange Inc; user contributions licensed under CC BY-SA. How to call PHP function on the click of a Button ? Once enabled, the strict mode affects the execution context, making this to be undefined in a regular function invocation. Novice developers sometimes believe a leading-zero prefix has no semantic meaning, so they might use it as an alignment device but this changes the number's meaning! What was the purpose of laying hands on the seven in Acts 6:6. Gentle Explanation of "this" in JavaScript google apps script: get the name of the function that is currently running. Copy and paste console.debug(arguments.callee) is more convenient ( I do not need to repeat function name). Example 1: This example display currently running function using arguments.callee method. Using the function.caller Property In this approach, we will use the function.caller property in JavaScript. However, arguments.callee.name is only available from inside the function. In normal code arguments.callee refers to the enclosing function. When a function is called in non-strict mode, this refers to the global object which is a window in the browser and global on Node.js. In sloppy mode, a function declaration inside a block may be visible outside the block and even callable. How to change selected value of a drop-down list using jQuery? Can I get the name of the currently running function in JavaScript? Why do you need to get the name of the function ? Asking for help, clarification, or responding to other answers. How to get the function name under "use strict"? Note: Nested functions cease to be source elements, and are hence not hoisted. Which ability is most related to insanity: Wisdom, Charisma, Constitution, or Intelligence? In a sloppy mode function whose first argument is arg, setting arg also sets arguments[0], and vice versa (unless no arguments were provided or arguments[0] is deleted). How do I get the current date in JavaScript? How to get currently running function name using JavaScript assigning values to non-writable properties. arguments objects for strict mode functions store the original arguments when the function was invoked. What does "up to" mean in "is first up to launch"? In strict mode, it is now undefined. Why doesnt a Javascript return statement work when the return value is on a new line. Strict mode has been designed so that the transition to it can be made gradually. This is the same answer you got before, just wrapped up in a nice module, and using some V8-specific APIs. Creating Error object for each calling is just a hack, not a working method. throw myFunctionName() + ': invalid number of arguments'; For now I have to hard-code the function name within the throws. The non-strict plus strict looks non-strict. Its possible that you are approaching the problem wrong. arguments.callee for strict mode functions is a non-deletable property which throws an error when set or retrieved: Reserved words are identifiers that can't be used as variable names. Get name and line of calling function in node.js - JavaScript Why? was passed to each function. How to calculate the number of days between two dates in JavaScript ? Not only is automatic boxing a performance cost, but exposing the global object in browsers is a security hazard because the global object provides access to functionality that "secure" JavaScript environments must restrict. Thanks for contributing an answer to Stack Overflow! If total energies differ across different software, how do I decide which software to use? property, a non-existing property, a non-existing variable, or a non-existing Connect and share knowledge within a single location that is structured and easy to search. How can one get the name and line of a function that called the current one? Moreover . Then I create an object obj1 and put my function there. what I want is that the alert inside de error scoope shows the function name, in this case "MyFunction" but instead what I get is the error:function. Strict mode makes it easier to write secure JavaScript. This is mainly for security reasons and sadly currently there's no alternative for this. There may also be large incompatibilities between implementations and the behavior may change in the future. Though, in some implementations you can simply get the name using arguments.callee.name. Confirmed working in Node v16.13.0. For this, just out exact statement "use strict"; at the start of the script that is before any other statements. Given a function and the task is to get the name of function that is currently running using JavaScript. notation to access it. There are some chances is not even working there. To enable strict mode for your javascript code, all you have to do is add the string "use strict" at the beginning of the code. Can I use my Coinbase address to receive bitcoin? Embedded hyperlinks in a thesis or research paper, Short story about swapping bodies as a job; the person who hires the main character misuses his body. Most current browsers support a name property on Function objects that was non-standard until ES2015, but no current version of IE does. As we know, if we define functions as properties of objects, they are referred to as methods.If a method uses "this" keyword, it refers to that object and can be used to refer/access the properties of the object.Let's understand its usage with the help of the following . Strict Mode with 'use strict' in JavaScript - Studytonight In ES5 and above, there is no access to that information. StackExchange.ready(function(){$.get("https://stackoverflow.com/posts/38435450/ivc/7a17");}); Read More how to monitor the network on node.js similar to chrome/firefox developer tools?Continue, Read More Call AngularJS from legacy codeContinue, Read More How can I add multiple sources to an HTML5 audio tag, programmatically?Continue, Read More webpack: Module not found: Error: Cant resolve (with relative path)Continue, Read More Why doesnt a Javascript return statement work when the return value is on a new line?Continue, Read More How to set time with date in momentjsContinue, The answers/resolutions are collected from stackoverflow, are licensed under. Third, arguments.callee is no longer supported. You can screen for such errors at the function granularity level. All browser compatibility updates at a glance, Frequently asked questions about MDN Plus. The purpose of "use strict" is to indicate that the code should be executed in "strict mode". We also share information about your use of our site with our social media, advertising and analytics partners. Not using eval if you don't really need it may be another pragmatic solution. Tutorials, references, and examples are constantly reviewed to avoid errors, but we cannot warrant full correctness of all content. It can be applied to individual functions. In older versions of JS you can get it by using arguments.callee. Both involve a considerable amount of magical behavior in sloppy mode: eval to add or remove bindings and to change binding values, and arguments syncing named arguments with its indexed properties. The fact that you want the function name is probably a good indication that you're thinking about the problem incorrectly. If the object is not specified, functions in strict mode See ; non-standard and not allowed in strict mode, developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/. But arguments.callee.name only works in loose mode. What is THIS keyword in JavaScript and How to use it with Examples? The entire concatenation looks strict, the inverse is also true. Asking for help, clarification, or responding to other answers. This strict context prevents certain actions from being taken and throws more exceptions. For strict, arrow, async, and generator functions, accessing the caller property throws a TypeError. Table Of Contents duplicating parameter in regular JS function; duplicating parameter in non strict mode; duplicating parameter in strict mode; How do arrow functions treat duplicate parameters Generic Doubly-Linked-Lists C implementation. This isn't an official term, but be aware of it, just in case. Using Strict mode for the entire script: To invoke strict mode for an entire script, put the exact statement use strict; (or use strict;) before any other statements. eval code, Function code, event handler attributes, strings passed to setTimeout(), and related functions are either function bodies or entire scripts, and invoking strict mode in them works as expected. Perfect. I've got the Dojo and jQuery frameworks in my stack, so if either of those make it easier, they're available. Visit Mozilla Corporations not-for-profit parent, the Mozilla Foundation.Portions of this content are 19982023 by individual mozilla.org contributors. Why is it shorter than a normal address? What does the power set mean in the construction of Von Neumann universe? javascript - How to get function name in strict mode [proper way *only with JSON Schema ** only with JSON Type Definition # Strict mode options v7 # strict By default Ajv executes in strict mode, that is designed to prevent any unexpected behaviours or silently ignored mistakes in schemas (see Strict Mode for more details). Here's what happens when you use code based on it: You'll then be able to reference obj1.func.name and it'll return 'test1'. Knowing the name of the current function can be essential if that function is being created dynamically from a database and needs context information inside the function that is keyed to the function name. In general you want to invoke strict mode because of its benefits to your code's reliability (see @JohnResig article). var functionName = function() {} vs function functionName() {}. A leading-zero syntax for the octal is rarely useful and can be mistakenly used, so strict mode makes it a syntax error: The standardized way to denote octal literals is via the 0o prefix. assignment to a non-writable data property, assignment to a getter-only accessor property, Declaring two function parameters with the same name, Declaring the same property name twice in an object literal, Assigning to an undeclared variable throws a, Failing to assign to an object's property (e.g. The following code checks the value a function's caller property. I would like to have a rudimentary debugging function like this (with npmlog defining log.debug ): 6 1 function debug() { 2 var callee, line; 3 /* MAGIC */ 4 log.debug(callee + ":" + line, arguments) 5 } 6 When called from another function it would be something like this: Beginner kit improvement advice - which lens should I consider? Connect and share knowledge within a single location that is structured and easy to search. To learn more, see our tips on writing great answers. How to have multiple colors with a single material on a single object? Get certifiedby completinga course today! Also, to get only the name of the function, you need to use arguments.callee.name. ))?$/g, '$1 ($2:$3)' ). This is why W3C's attempts to deprecate tags like and has failed. It's just a different UI. Declaring Strict Mode Strict mode is declared by adding "use strict"; to the beginning of a script or a function. In strict mode code, eval doesn't create a new variable in the scope from which it was called. On whose turn does the fright from a terror dive end? The JavaScript `this` Keyword + 5 Key Binding Rules Explained for JS Attempts to delete a non-configurable or otherwise undeletable (e.g. Can you still use Commanders Strike if the only attack available to forego is an attack against an ally? Moreover, arguments.callee substantially hinders optimizations like inlining functions, because it must be made possible to provide a reference to the un-inlined function if arguments.callee is accessed. It is thus recommended that you enable strict mode on a function-by-function basis (at least during the transition period). Compiling a numeric literal (4 + 5;) or a string literal ("John Doe";) in a Strict mode makes it impossible to accidentally create global variables. One interesting way I'm experimenting with is a declaration like the following: It's a little hacky, but what ends up happening is test1 is a local variable that holds a [Function: test1] object. To learn more, see our tips on writing great answers. How do you find out the caller function in JavaScript How to get currently running function name using JavaScript ? JavaScript: How to get the caller (parent) function's name BCD tables only load in the browser with JavaScript enabled. In normal JavaScript, a developer will not receive any error feedback Let's understand all these usage and values of "this" in various contexts:What does "this" refers to when used in a method? Used in global scope for the entire script. It simply compiles to a non existing What is JavaScript Strict mode and how can we enable it ? after: In sloppy mode, eval("var x;") introduces a variable x into the surrounding function or the global scope. How to enforce strict null checks in TypeScript ? Oh that's why people always beat me on the speed to reply. "strict mode". How to flip an image on hover using CSS ? Not the answer you're looking for? Sometimes this fixes the immediate problem, but sometimes this creates worse problems in the future. How to display the tag name of the clicked element using jQuery ? When a function fun is in the middle of being called, fun.caller is the function that most recently called fun, and fun.arguments is the arguments for that invocation of fun. To subscribe to this RSS feed, copy and paste this URL into your RSS reader. Use of reserved keywords as variable or function name. Download ZIP [NodeJS] Get the current function name or any other function while using strict mode Raw functionName.js 'use strict'; const findFirstOccurrence = (string, searchElements, fromIndex = 0) => { let min = string.length; for (let i = 0; i < searchElements.length; i += 1) { const occ = string.indexOf (searchElements [i], fromIndex); In sloppy mode, mistyping a variable in an assignment creates a new property on the global object and continues to "work".