On the foreach and each in JavaScript

foreach is a method of manipulating an array in ES5, and the main function is to iterate through the array, for example:

　　

var arr = [1,2,3,4];arr.foreach (alert);

Equivalent to:

var arr = [1, 2, 3, 4];for (var k = 0, length = arr.length; k < length; k++) {alert (array[k]);}

The function callback in the Foreach method has three parameters: the first argument is the array contents of the traversal, the second parameter is the corresponding array index, and the third parameter is the array itself

So:

[].foreach (function (Value,index,array) {

Code something

});

Equivalent to:

$.each ([],function (Index,value,array) {

Code something

})

Write an example;

var arr = [1,2,3,4];arr.foreach (function (value,index,array) {    Array[index] = = value;    The result is true    sum+=value;       }); Console.log (sum);    Result is 8

Map:map is a "map" that uses the same meaning as a forEach, using the following:

[].map (function (Value,index,array) {

Code

})

On the foreach and each in JavaScript