Use and introduction of the JavaScript forEach () traversal function, javascriptforeach

Use and introduction of the JavaScript forEach () traversal function, javascriptforeach

The forEach () function traverses the array from start to end. There are three parameters: array element, element index, and array (if a parameter is an array element, it is the value of the array.

Var data = [1, 2, 3, 4, 5, 6]; var sum = 0; data. forEach (function (v) {// where v is the array value 123456sum + = v;}) document. write (sum + "<br>"); // print out 21data. forEach (function (o, p, q) {// corresponds to array elements, element indexes, array itself q [p] = o + 1;}) document. write (data );

Note: forEach cannot terminate before all elements are passed to the called function (while the for loop has a break method). To terminate the function in advance, you must put forEach in the try block, and can throw an exception. If a forEach. break exception is thrown by a function called by foreach (), the loop is terminated in advance:

Function foreach (a, B, c) {try {. forEach (B, c);} catch (e) {if (e = foreach. break) return; else throw e ;}} foreach. break = new Error ("StopIteration ");}