JavaScript获取多个数组的交集简单实例

内容摘要
在项目中需要取得多个数组的交集，故本例只是适用于特定场景。比如A数组 var a = {1000,10001,10002,10003}; B数组 var b = {10002, 10003}; C数组var c = {10003}; 需要取得
文章正文
在项目中需要取得多个数组的交集，故本例只是适用于特定场景。比如A数组 var a = {1000,10001,10002,10003}; B数组 var b = {10002, 10003}; C数组var c = {10003}; 需要取得这三个数组的交集数组。
      具体思路为：先初始一个最小数组为A数组,元素个数最小的也是数组A的长度.然后再迭代各个数组,取得这几个数组长度最短的为最小长度,同时得到长度最短数组。然后,迭代最小数组与各个数组,开始比较元素相等,使用计数器来判断是否该元素在各个数组中都存在即为交集元素.
      思路比较简单,但是可以实现多数组取得交集,代码如下：

复制代码 代码如下:

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN">
<HTML>
 <HEAD>
  <TITLE> New Document </TITLE>
  <META NAME="Generator" CONTENT="EditPlus">
  <META NAME="Author" CONTENT="">
  <META NAME="Keywords" CONTENT="">
  <META NAME="Description" CONTENT="">
  <script>
        function getValues(obj){    
            var values = "";
            var l = obj.options.length;
            for (var i=0; i<l; i++) {
                if (i != (l-1)) {
                    values += obj.options(i).value + "_";
                }
                else {
                    values += obj.options(i).value;
                }
            }
            return values;
        }

        function _test() {
            var ids = getValues(document.all.aa);
            var aa = _getIntersection(ids);
        }

        function _getIntersection(src) {
            var tAry = src.split("_");
            //最小数组
            var minAry = null;
            var min = tAry[0].split(",").length; //初始化第一个为长度最小的数组
            minAry = tAry[0].split(",");
            for (var i = 1, len = tAry.length; i<len; i++) {
                var temp = tAry[i].split(",");
                if (temp.length < min) {
                    min = temp.length;
                    minAry = temp;
                } 
            }
            alert("最小数组："+minAry);

            var ret = '';
            for (var i = 0, len = minAry.length; i<len; i++) {
                var srcNum = parseInt(minAry[i]);
                var counter = 0;
                for (var j = 0, ll = tAry.length; j<ll; j++) {
                    var tt = tAry[j].split(",");
                    for (var k = 0, l = tt.length; k<l; k++) {
                        var tarNum = parseInt(tt[k]);
                        if (srcNum == tarNum) {
                            counter ++;
                        }
                    }
                }
                if (counter == tAry.length) {
                    ret += srcNum + ",";
                }
            }
            ret = strSlice(ret, ',');
            alert("交集是：" + ret);
        }

        //去掉结尾分隔符
        function strSlice(str, split){
            if ((str!=null && str!="") && (split!=' '))
                return ((str.charAt(str.length-1) == split) ? str.substring(0, str.length-1) : str);
            else
                return str;
        }
  </script>

 </HEAD>

 <BODY>
    <button onclick="javascript:_test();">测试</button>

    <select name="aa" id="aa" size="6" multiple>
        <OPTION value="10004,10005,10008,10009,10010,10018">测试1</OPTION>
        <OPTION value="10004,10005,10006,10008,10009,10010,10018">测试2</OPTION>
        <OPTION value="10004,10005,10006,10008,10009,10010,10018">测试3</OPTION>
        <OPTION value="10004,10006,10008">测试4</OPTION>
        <OPTION value="10004,10010,10018">测试5</OPTION>
    </select>

 </BODY>
</HTML>
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