JS实现集合去重交集并集差集功能实例分享

function array_remove_repeat(a) { // 去重
 var r = [];
 for(var i = 0; i < a.length; i ++) {
 var flag = true;
 var temp = a[i];
 for(var j = 0; j < r.length; j ++) {
 if(temp === r[j]) {
 flag = false;
 break;
 }
 }
 if(flag) {
 r.push(temp);
 }
 }
 return r;
}
function array_intersection(a, b) { // 交集
 var result = [];
 for(var i = 0; i < b.length; i ++) {
 var temp = b[i];
 for(var j = 0; j < a.length; j ++) {
 if(temp === a[j]) {
 result.push(temp);
 break;
 }
 }
 }
 return array_remove_repeat(result);
}
function array_union(a, b) { // 并集
 return array_remove_repeat(a.concat(b));
}
function array_difference(a, b) { // 差集 a - b
 //clone = a
 var clone = a.slice(0);
 for(var i = 0; i < b.length; i ++) {
 var temp = b[i];
 for(var j = 0; j < clone.length; j ++) {
 if(temp === clone[j]) {
 //remove clone[j]
 clone.splice(j,1);
 }
 }
 }
 return array_remove_repeat(clone);
}
a = [1,2,3,4,5];
b = [3,4,5,6,7];
c = array_intersection(a, b);
d = array_union(a, b);
e = array_difference(a, b);
f = array_difference(b, a);
console.log("test array a:", a, " b:", b);
console.log("a & b :", c);
console.log("a + b :", d);
console.log("a - b:", e);
console.log("b - a:", f);

stephen@stephen:~/openstack/demo/nodejs$ node set_operation.js
test array a: [ 1, 2, 3, 4, 5 ] b: [ 3, 4, 5, 6, 7 ]
a & b : [ 3, 4, 5 ]
a + b : [ 1, 2, 3, 4, 5, 6, 7 ]
a - b: [ 1, 2 ]
b - a: [ 6, 7 ]