JavaScript中数组的交集

Question

I have array something like this:

var array1 = [
          {"name":"a","groups":["xxx","yyy"]},
          {"name":"abc","groups":["xxx","yyy"]},
          {"name":"abcd","groups":["zzz","xxx","yyy"]}
        ];

and

var array2 = ["xxx","yyy"];

I need to return the entire index of array1 when both "xxx" and "yyy" of array2 matches only to the "xxx" and "yyy" of array1.

Like in this example, it should only return array1[0] and array1[1]. Any help will be greatly appreciated. Thank you.

Answer 1

Modern JS would be:

 function filter(array1, array2) { // to filter array1 based on array2 return array1.filter(function(elt) { // retain an elt in array1 var groups = elt.groups; // if its groups property return groups.length === array2.length && // has the same length as array2 groups.every(function(e) { // and every element in it return array2.indexOf(e) > -1; // is found in array2 }); }); } var array1 = [ {"name":"a","groups":["xxx","yyy"]}, {"name":"abc","groups":["xxx","yyy"]}, {"name":"abcd","groups":["zzz","xxx","yyy"]} ]; var array2 = ["xxx","yyy"]; document.writeln(JSON.stringify(filter(array1, array2))); 

Answer 2

var array1 = [
          {"name":"a","groups":["xxx","yyy"]},
          {"name":"abc","groups":["xxx","yyy"]},
          {"name":"abcd","groups":["zzz","xxx","yyy"]}
        ];


var array2 = ["xxx","yyy"];

function checkArrays( arrA, arrB ){
    //check if lengths are different
    if(arrA.length !== arrB.length) return false;
    //slice so we do not effect the orginal
    //sort makes sure they are in order
    var cA = arrA.slice().sort(); 
    var cB = arrB.slice().sort();
    for(var i=0;i<cA.length;i++){
         if(cA[i]!==cB[i]) return false;
    }
    return true;
}



for (var i in array1){
    if (checkArrays(array1[i].groups, array2)){
        alert(array1[i]);
    }
}

http://jsfiddle.net/hh1tyy5e/

JavaScript does not have built in list comparison method.
Anyways, above is working code that will alert the desired elements from array1

Answer 3

I used stringify for comparison so the code doesn't change for a generic "something inside an object property" (ie the content of "groups" - or whatever) - performance could be better if you use direct compares.

var array1 = [
  {"name":"a","groups":["xxx","yyy"]},
  {"name":"abc","groups":["xxx","yyy"]},
  {"name":"abcd","groups":["zzz","xxx","yyy"]}
];

var testgroup = ["xxx", "yyy"];
var tg = JSON.stringify(testgroup);

var filteredArray = array1.filter(function (el) {
    if (JSON.stringify(el.groups) == tg) return el;
});
alert(JSON.stringify(filteredArray));