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Jul 23, 2014 · This is an arrow function. Arrow functions are a short syntax, introduced by ECMAscript 6, that can be used similarly to the way you would use function expressions. In other words, you can often use them in place of expressions like function (foo) {...}. But they have some important differences.
1. this will always refer to the global object when used inside an arrow function. Use the regular function declaration to refer to the local object. Also, you can use the object name as the context (object.method, not this.method) for it to refer to the local object instead of the global (window).
Apr 8, 2014 · This has two benefits: (1) It is less awkward to write function foo(){} than const foo = () => {} — in particular outside other function calls. (2) The function name shows in stack traces. While it would be tedious to name every internal callback, naming all the public functions is probably a good idea.
Mar 2, 2015 · Longer answer: Arrow functions do not have this, arguments or other special names bound at all - when the object is being created the name this is found in the enclosing scope, not the person object. You can see this more clearly by moving the declaration: var person = {. name: "Jason". }; person.shout = () => console.log("Hi, my name is", this);
Feb 1, 2022 · An arrow function can simply be seen as a concise version of a regular function, except that the return is implied (among a few other subtle things you can read about here). One nice way to use an if/else is though a ternary .
May 21, 2021 · Using async method inside of a class: // do something. The OP appears to be looking for a named, async, arrow function which is the one syntax you do not show. Actually, const foo = async () => {} creates a named async function named foo. It's entirely possible to do named functions this way (just no hoisting).
Jan 4, 2016 · Isn’t the arrow function already an expression by default?! and this is the Kyle Simpson's answer: an arrow function is an expr, but we need surrounding parens b/c of "operator precedence" (sorta), so that the final parens to invoke the arrow-IIFE apply to the entire function and not to just the last token of its body.
Arrow functions and function declarations / expressions are not equivalent and cannot be replaced blindly. If the function you want to replace does not use this, arguments and is not called with new, then yes. As so often: it depends. Arrow functions have different behavior than function declarations / expressions, so let's have a look at the ...
Arrow functions allow you to have an implicit return: values are returned without having to use the return keyword. It works when there is a on-line statement in the function body: const myFunction = () => 'test'. console.log(myFunction()) //'test'.
Feb 24, 2019 · In the "non-working" code, you're passing a function that returns a function (callback) to forEach. callback itself is never called. This would actually call the function, but it is basically the same as directly passing callback directly to forEach as in your first example: ary.forEach((i) => callback(i));
