ES5的寫法 ``` var a = [1,2,3,4,5] var b = [2,4,6,8,10] //交集 var c = a.filter(function(v){ return b.indexOf(v) > -1 }) //差集 var d = a.filter(function(v){ return b.indexOf(v) == -1 }) //補集 var e = a.filter(function(v){ return !(b.indexOf(v) > -1) }).concat(b.filter(function(v){ return !(a.indexOf(v) > -1) })) //并集 var f = a.concat(b.filter(function(v){ return !(a.indexOf(v) > -1) })); console.log("數組a：", a); console.log("數組b：", b); console.log("a與b的交集：", c); console.log("a與b的差集：", d); console.log("a與b的補集：", e); console.log("a與b的并集：", f); ```  用ES6 的寫法 ``` var a = [1,2,3,4,5] var b = [2,4,6,8,10] console.log("數組a：", a); console.log("數組b：", b); var sa = new Set(a); var sb = new Set(b); // 交集 let intersect = a.filter(x => sb.has(x)); // 差集 let minus = a.filter(x => !sb.has(x)); // 補集 let complement = [...a.filter(x => !sb.has(x)), ...b.filter(x => !sa.has(x))]; // 并集 let unionSet = Array.from(new Set([...a, ...b])); console.log("a與b的交集：", intersect); console.log("a與b的差集：", minus); console.log("a與b的補集：", complement); console.log("a與b的并集：", unionSet); ``` ## **方法2：對 Array 進行擴展** ``` //數組迭代函數 Array.prototype.each = function(fn){ fn = fn || Function.K; var a = []; var args = Array.prototype.slice.call(arguments, 1); for(var i = 0; i < this.length; i++){ var res = fn.apply(this,[this[i],i].concat(args)); if(res != null) a.push(res); } return a; }; //數組是否包含指定元素 Array.prototype.contains = function(suArr){ for(var i = 0; i < this.length; i ++){ if(this[i] == suArr){ return true; } } return false; } //不重復元素構成的數組 Array.prototype.uniquelize = function(){ var ra = new Array(); for(var i = 0; i < this.length; i ++){ if(!ra.contains(this[i])){ ra.push(this[i]); } } return ra; }; //兩個數組的交集 Array.intersect = function(a, b){ return a.uniquelize().each(function(o){return b.contains(o) ? o : null}); }; //兩個數組的差集 Array.minus = function(a, b){ return a.uniquelize().each(function(o){return b.contains(o) ? null : o}); }; //兩個數組的補集 Array.complement = function(a, b){ return Array.minus(Array.union(a, b),Array.intersect(a, b)); }; //兩個數組并集 Array.union = function(a, b){ return a.concat(b).uniquelize(); }; ``` 使用： ``` var a = [1,2,3,4,5] var b = [2,4,6,8,10] console.log("數組a：", a); console.log("數組b：", b); console.log("a與b的交集：", Array.intersect(a, b)); console.log("a與b的差集：", Array.minus(a, b)); console.log("a與b的補集：", Array.complement(a, b)); console.log("a與b的并集：", Array.union(a, b)); ``` ## **方法三：使用 jQuery 實現** 如果項目中有引入 jQuery，那么實現起來也很簡單。 ``` var a = [1,2,3,4,5] var b = [2,4,6,8,10] console.log("數組a：", a); console.log("數組b：", b); // 交集 let intersect = $(a).filter(b).toArray(); // 差集 let minus = $(a).not(b).toArray(); // 補集 let complement = $(a).not(b).toArray().concat($(b).not(a).toArray()); // 并集 let unionSet = $.unique(a.concat(b)); console.log("a與b的交集：", intersect); console.log("a與b的差集：", minus); console.log("a與b的補集：", complement); console.log("a與b的并集：", unionSet); ```