apply method
The apply method allows you to
call a function with a given context.
The first parameter of the method
should be the context of the function,
and the second - the array of function
parameters.
Syntax
function.apply(context, array of parameters);
Example
Let us have an input:
<input id="elem" value="text">
Let also be given a function taking three parameters:
function func(param1, param2, param3) {
console.log(this.value + param1 + param2 + param3);
}
Let's call our function so that this
inside the function is equal to our input,
and at the same time passing it the numbers
1, 2 and 3:
let elem = document.querySelector('#elem');
func.apply(elem, [1, 2, 3]);
Example
Let a function take no parameters:
function func() {
console.log(this.value);
}
In this case, when calling this function
through apply, it is enough to pass only
the first parameter with the context:
let elem = document.querySelector('#elem');
func.apply(elem);