I have an array and now I want to execute a function on every element in the array.
I'm trying to use map() function. The question is, my callback function passed to map() has its own parameters (not element, index, array).
Can I pass parameters to such a callback function? How?
I can think of 2 different ways:
Using thisArg to set an options object as the this value in the callback:
var numbers = [1,2,3,4,5,6,7,8,9,10];
function callback(element) {
return element + this.add;
};
var mapped = numbers.map(callback, {
add: 10
});
console.log(mapped);Using .bind() to set some arguments:
var numbers = [1,2,3,4,5,6,7,8,9,10];
function callback(add, element) {
return element + add;
};
var mapped = numbers.map(callback.bind(null, 10));
console.log(mapped);
this object to the callback. What is this this referring to?this is used to refer to the object a function is called as a method of. The array map method allows specifying what that this object should be, as it is not calling the function as a method this can be very useful. In this case, I just set a specific this value that is my own object. This question goes into more detail on the this object: How does the “this” keyword work?
I think you might need to wrap your original function in another callback function, like this:
var array = ['one', 'two', 'skip-a-few', 'three', 'four']
console.log(
array.map(function (element) {
return original('other', 'variables', element)
})
)
// this function doesn't matter, just an example
function original(a, b, c) {
return a + ' ' + b + ' ' + c
}
map((elm, index) => { func(params); })?(arg1, arg2, /*etc*/,element,index,array)