JS JavaScript Array retrieves the specified element index, determines whether the same, duplicates, and filters data

Recently, many JavaScript codes have been written, and many methods in array are insufficient. It may be used after you add it yourself. <Br/> <SCRIPT type = "text/JavaScript"> <br/> // locate the returned index.-1 is returned if no index exists. <br/> array. prototype. index = function (EL) {<br/> var I = 0; <br/> for (VAR I = 0, Len = This. length; I <Len; I ++) {<br/> If (El = This [I]) {<br/> return I; <br/>}< br/> return-1; <br/>}; </P> <p> // whether the same is true, different return values: false <br/> array. prototype. same = function () {<br/> If (this. length = 0) {<br/> return true; <br/>}< br/> VaR Temp = This. Join (''). replaceall (this [0]," "); <br/> If (temp! = "") {<Br/> return false; <br/>}else {<br/> return true <br/>}< br/> }; <br/> // replaceall function reference: http://blog.csdn.net/IBM_hoojo/archive/2010/06/17/5675096.aspx </P> <p> // determine whether duplicate data exists <br/> array. prototype. iterate = function () {<br/> var flag = false; <br/> for (VAR I = 0, Len = This. length; I <Len; I ++) {<br/> for (VAR J = 0; j <Len; j ++) {<br/> If (this [I] = This [J] & I! = J) {<br/> flag = true; <br/> break; <br/>}< br/> return flag; <br/>}; </P> <p> // input a callback and filter the Array Based on the callback function conditions. <br/> array. prototype. filter = function (callback) {<br/> var rs = []; <br/> for (VAR I = 0, length = This. length; I <length; I ++) {<br/> If (callback (this [I], I) {<br/> Rs. push (this [I]); <br/>}< br/> Return Rs; <br/>}; </P> <p> window. onload = function () {<br/> var ary = [1, 2, 3, 4, 6, 4, 5]; <br/> alert (ary. index (6); <br/> alert (ary. same (); <br/> alert (ary. iterate (); <br/> var A = ary. filter (function (n, I) {<br/> return n> 4; <br/>}); </P> <p> alert (. length + "-" + A [0]); <br/>}< br/> </SCRIPT>