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.jstest 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 ]