JavaScript Function Application

The apply() method calls a function with the given this value and provides parameters in the form of an array (or an object similar to an array).

let numbers = [5,　6,　2,　3,　7];
let max = Math.max.apply(null, numbers);
document.write(max);

The difference between call() and apply()

The call() method accepts parameters separately.

The apply() method takes parameters asArray.

If you want to use an array instead of a parameter list, the apply() method is very convenient.

Using apply() and built-in functions

Useful in conjunction with apply(), you can use built-in functions for certain tasks that might otherwise be written by iterating over array values.

As an example, we will use Math.max/ Find the Maximum Value in the Array Using Math.max/Minimum Value.

let numbers = [5,　6,　2,　3,　7];
let max = Math.max.apply(null, numbers);
let min = Math.min.apply(null, numbers);
for(let i = 0; i < numbers.length; i++) {
　　　if(numbers[i] > max) {
　max = numbers[i];
　　　}
　　　if(numbers[i] < min) {
　min = numbers[i];
　　　}
}
document.write(min, "<br>", max);

Calling a Function with apply() Without Specifying Parameters

In the following example, we call the display function without passing any parameters:

var name = "Seagull";
function display() {
　　document.write(this.name);
}
display.apply();