Is there a way to name arrow functions in JavaScript?

Question

I'm using arrow functions in an app and sometimes there is the need to get a reference to the function itself. For normal JavaScript functions, I can just name them and use the name from within. For arrow functions, I'm currently using arguments.callee. Is there a way to name arrow functions so that a reference can be used from within?

Sample code

// TypeScript
private evaluateIf(expr: parserModule.IIfExpression, callback: IEnvCallback) {
    this.evaluate(expr.condition, proceed => {
        guard(arguments.callee, arguments, this);
        if (proceed !== false) this.evaluate(expr.then, callback);
        else if (expr.else) this.evaluate(expr.else, callback);
        else callback(false);
    });
}

// JavaScript
Environment.prototype.evaluateIf = function (expr, callback) {
    var _this = this;
    this.evaluate(expr.condition, function (proceed) {
        guard(arguments.callee, arguments, _this);
        if (proceed !== false)
            _this.evaluate(expr.then, callback);
        else if (expr.else)
            _this.evaluate(expr.else, callback);
        else
            callback(false);
    });
};

What I settled on after the assistance since arguments might not be there forever:

private evaluateIf(expr: parserModule.IIfExpression, callback: IEnvCallback) {
    var fn;
    this.evaluate(expr.condition, fn = proceed => {
        guard(fn, [proceed], this);
        if (proceed !== false) this.evaluate(expr.then, callback);
        else if (expr.else) this.evaluate(expr.else, callback);
        else callback(false);
    });
}

Isn't the main point of arrow functions just a more succinct way of expressing anonymous functions, with the correct this binding? Hence they wouldn't have names with the JS equivalent anyway. — GregL
– GregL, Commented Mar 26, 2015 at 0:11
Looks like you don't want arrow functions after all, but a named function expression. — Felix Kling
– Felix Kling, Commented Mar 26, 2015 at 0:14
Nah. Actually I want to use the arrow functions and they are working well. However I'm implementing a piece of code (following a tutorial) that requires that I use the calling function as part of a guarding process. I want to know the way to avoid using arguments.callee while at the same time avoiding having to go and change each function that is affected to a normal javascript function. — ritcoder
– ritcoder, Commented Mar 26, 2015 at 0:34
named functions are also handy for stack traces aside from needing to reference them — Askdesigners
– Askdesigners, Commented Jun 4, 2019 at 19:33

Peter Mortensen · Accepted Answer · 2021-05-21 18:49:57Z

18

Is there a way to name arrow functions so that a reference can be used from within?

Not unless you assign it to a variable. For example:

var foo = () => {
    console.log(foo);
}

For arrow functions, I'm currently using arguments.callee

arguments are not supported by arrow functions. TypeScript currently incorrectly allows you to use them. This will be an error in the next version of TypeScript. This is to keep TypeScript arrow functions compatible with the JavaScript Language Specification.

For your use case I would just use a function.

edited May 21, 2021 at 18:49

Peter Mortensen

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answered Mar 26, 2015 at 0:12

basarat

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5 Comments

ritcoder Over a year ago

Oh ok. So my code is working now because typescript is currently not converting them to es6. Since typescript is converting it to plain javascript, is there a way to get it to assign a name to the function it generates? I have some sample code so will edit the question and add it since it is not well formatted

basarat Over a year ago

Sorry I was unclear. arguments are going to be an error irrespective of which version (es6,es5,es3) you are targeting. I've updated my answer

basarat Over a year ago

@ritcoder I've also added a code sample to explain what I meant with assign to a variable

ritcoder Over a year ago

Thanks. I did not know that. I guess I'll have to use normal functions for those portions then.

ritcoder Over a year ago

Yeah. As in your code sample, it actually worked expect that I had to declare a variable outside the function to use it but I'm ok. I've edited the question to show the updated code.

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