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：
<!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 onclick="javascript:_test();">測試</button>
<select name="aa" id="aa" 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>
