JavaScript獲取多個數組的交集簡單實例

2024-05-06 15:54:42

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這篇文章介紹了JavaScript獲取多個數組的交集簡單實例，有需要的朋友可以參考一下

在項目中需要取得多個數組的交集，故本例只是適用于特定場景。比如A數組 var a = {1000,10001,10002,10003}; B數組 var b = {10002, 10003}; C數組var c = {10003}; 需要取得這三個數組的交集數組。
具體思路為：先初始一個最小數組為A數組,元素個數最小的也是數組A的長度.然后再迭代各個數組,取得這幾個數組長度最短的為最小長度,同時得到長度最短數組。然后,迭代最小數組與各個數組,開始比較元素相等,使用計數器來判斷是否該元素在各個數組中都存在即為交集元素.
思路比較簡單,但是可以實現多數組取得交集,代碼如下：

復制代碼代碼如下:

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN">
<HTML>
<HEAD>
<TITLE> New Document </TITLE>
<META CONTENT="EditPlus">
<META CONTENT="">
<META CONTENT="">
<META 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("_");
            //最小數組
            var minAry = null;
            var min = tAry[0].split(",").length; //初始化第一個為長度最小的數組
            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("最小數組："+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);
        }

        //去掉結尾分隔符
        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>測試</button>

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

</BODY>
</HTML>