如何从javascript中的var数组列表中获取不同的值 [英] how to get distinct value from var array list in javascript

问题描述

if (_arrCheckpoints.length > 0) {
    var _yr = new Array();
   for (var i = 0; i < _arrCheckpoints.length; i++) {
   var _Ayr = _arrCheckpoints[i].substring(_arrCheckpoints[i].length - 4) 
   _yr.push(_Ayr);
       }

}

  output _yr = 2014
               2014
               2014
               2013
               2013 
               2013


  i need _yr = 2014
               2013

推荐答案

请尝试：



不使用库的示例。这需要两个新的原型函数，包含和唯一的

Please try:

Example that uses no libraries. This requires two new prototype functions, contains and unique

Array.prototype.contains = function(v) {
    for(var i = 0; i < this.length; i++) {
        if(this[i] === v) return true;
    }
    return false;
};

Array.prototype.unique = function() {
    var arr = [];
    for(var i = 0; i < this.length; i++) {
        if(!arr.contains(this[i])) {
            arr.push(this[i]);
        }
    }
    return arr;
}

You can then do:

var duplicates = [1,3,4,2,1,2,3,8];
var uniques = duplicates.unique(); // result = [1,3,4,2,8]

For more reliability, you can replace contains with MDN's indexOf shim and check if each element's indexOf is equal to -1: https://developer.mozilla.org/en/JavaScript/Reference/Global_Objects/Array/indexOf

示例：点击此处

if (_arrCheckpoints.length > 0) {
                        var _yr = new Array();
                        var x = 0;
                        var _strHTML2 = "<div id='yrd'><ul class='nav'>";
                        for (var i = 0; i < _arrCheckpoints.length; i++) {

                            var _Ayr = _arrCheckpoints[i].substring(_arrCheckpoints[i].length - 4)

                            if (_yr != _Ayr) {

                                x++;
                                if (_yr[i-x] != _Ayr) {

                                    _yr.push(_Ayr);

                                }

                            }


                        }

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