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 })
For example:
var arr = [1,2,3,4];arr.foreach (function(value,index,array) { = = value; // result is true sum+=value; }); Console.log (sum); // The result is ten
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