I want to get a function's name in an arrow function
Actually, if we write
function abc(){
let funcName = arguments.callee.name
}
But in an arrow function
abc: ()=>{
let funcName = arguments.callee.name
}
funcName return ''
1 Answer
- Arrow functions do not have an
argumentsbinding. But they have access to the arguments object of the closest non-arrow parent function. Named and rest parameters are heavily relied upon to capture the arguments passed to arrow functions.
function dummy() {
return (() => arguments.callee.name)(); // dummy
}
- The value of
thisinside an arrow function remains the same throughout the lifecycle of the function and is bound to the value of the closestthis-providing environment.
const obj = {
// like a normal function, returns obj - defines like obj.a = function a() {};
a() { return this },
// arrow function uses global as this
b: () => { return this },
};
console.log(obj.a() == obj) // true
console.log(obj.b() == obj) // false
console.log(obj.b() == window) // true
- Arrow functions can never be used as constructor functions. Hence, they can never be invoked with the new keyword. As such, a prototype property does not exist for an arrow function.
Therefor, the only way to get the name of an arrow function is from accessing the direct reference to it.
const arrow = () => arrow.name;
console.log(arrow()); // "arrow"
const obj = {
a: () => obj.a.name;
}
console.log(obj.a()); // "a"
2 Comments
Bergi
Other than "your code code does not work (because arrow functions have no
arguments)", I don't see how this answers the question about getting the .name
Felix Kling
"is always bound to the value of
this in the closest non-arrow parent function." Probably good enough for most use cases but just for completeness: It's the closest "this-providing" environment, which can be the global environment or a module environment (not that those this values would be very interesting, but still).
12argumentsobject inside the arrow function?abcproperty of a parent object. You could just hard code it in the arrow function if you want.