是否有一种方法可以在JavaScript中返回两个数组之间的差异?
例如:
var a1 = ['a', 'b'];
var a2 = ['a', 'b', 'c', 'd'];
// need ["c", "d"]
是否有一种方法可以在JavaScript中返回两个数组之间的差异?
例如:
var a1 = ['a', 'b'];
var a2 = ['a', 'b', 'c', 'd'];
// need ["c", "d"]
当前回答
以下是我使用的方法:
var newArr = a1.filter(function(elem) {
return a2.indexOf(elem) === -1;
}).concat( a2.filter(function(elem) {
return a1.indexOf(elem) === -1;
}));
console.log(newArr);
或者这个
var newArr = a1.concat(a2);
function check(item) {
if (a1.indexOf(item) === -1 || a2.indexOf(item) === -1) {
return item;
}
}
return newArr.filter(check);
其他回答
在这种情况下,您可以使用Set。它针对这种操作(并、交、差)进行了优化。
确保它适用于你的案例,一旦它不允许重复。
var a = new JS.Set([1,2,3,4,5,6,7,8,9]);
var b = new JS.Set([2,4,6,8]);
a.difference(b)
// -> Set{1,3,5,7,9}
纯JavaScript解决方案(没有库) 与旧浏览器兼容(不使用过滤器) O (n ^ 2) 可选的fn回调参数,用于指定如何比较数组项
function diff(a, b, fn){ var max = Math.max(a.length, b.length); d = []; fn = typeof fn === 'function' ? fn : false for(var i=0; i < max; i++){ var ac = i < a.length ? a[i] : undefined bc = i < b.length ? b[i] : undefined; for(var k=0; k < max; k++){ ac = ac === undefined || (k < b.length && (fn ? fn(ac, b[k]) : ac == b[k])) ? undefined : ac; bc = bc === undefined || (k < a.length && (fn ? fn(bc, a[k]) : bc == a[k])) ? undefined : bc; if(ac == undefined && bc == undefined) break; } ac !== undefined && d.push(ac); bc !== undefined && d.push(bc); } return d; } alert( "Test 1: " + diff( [1, 2, 3, 4], [1, 4, 5, 6, 7] ).join(', ') + "\nTest 2: " + diff( [{id:'a',toString:function(){return this.id}},{id:'b',toString:function(){return this.id}},{id:'c',toString:function(){return this.id}},{id:'d',toString:function(){return this.id}}], [{id:'a',toString:function(){return this.id}},{id:'e',toString:function(){return this.id}},{id:'f',toString:function(){return this.id}},{id:'d',toString:function(){return this.id}}], function(a, b){ return a.id == b.id; } ).join(', ') );
下划线中的差分方法(或它的替换,Lo-Dash)也可以做到这一点:
(R)eturns the values from array that are not present in the other arrays
_.difference([1, 2, 3, 4, 5], [5, 2, 10]);
=> [1, 3, 4]
与任何下划线函数一样,你也可以以更面向对象的风格使用它:
_([1, 2, 3, 4, 5]).difference([5, 2, 10]);
var result = [];
var arr1 = [1,2,3,4];
var arr2 = [2,3];
arr1.forEach(function(el, idx) {
function unEqual(element, index, array) {
var a = el;
return (element!=a);
}
if (arr2.every(unEqual)) {
result.push(el);
};
});
alert(result);
只是想…为了一个挑战;-)这个工作…(对于字符串,数字等的基本数组)没有嵌套数组
function diffArrays(arr1, arr2, returnUnion){
var ret = [];
var test = {};
var bigArray, smallArray, key;
if(arr1.length >= arr2.length){
bigArray = arr1;
smallArray = arr2;
} else {
bigArray = arr2;
smallArray = arr1;
}
for(var i=0;i<bigArray.length;i++){
key = bigArray[i];
test[key] = true;
}
if(!returnUnion){
//diffing
for(var i=0;i<smallArray.length;i++){
key = smallArray[i];
if(!test[key]){
test[key] = null;
}
}
} else {
//union
for(var i=0;i<smallArray.length;i++){
key = smallArray[i];
if(!test[key]){
test[key] = true;
}
}
}
for(var i in test){
ret.push(i);
}
return ret;
}
array1 = "test1", "test2","test3", "test4", "test7"
array2 = "test1", "test2","test3","test4", "test5", "test6"
diffArray = diffArrays(array1, array2);
//returns ["test5","test6","test7"]
diffArray = diffArrays(array1, array2, true);
//returns ["test1", "test2","test3","test4", "test5", "test6","test7"]
注意排序可能不会像上面提到的那样…但是如果需要的话,可以在数组上调用.sort()对其进行排序。