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
困难的方法(如果你想做一些比.indexOf更奇特的东西)
var difference = function (source, target) {
return source.reduce(function (diff, current) {
if (target.indexOf(current) === -1) {
diff.push(current);
}
return diff;
}, []);
}
简单的方法
var difference = function (source, target) {
return source.filter(function (current) {
return target.indexOf(current) === -1;
});
}
其他回答
所选的答案只对了一半。您必须比较数组的两种方式才能得到完整的答案。
const ids_exist = [
'1234',
'5678',
'abcd',
]
const ids_new = [
'1234',
'5678',
'efjk',
'9999',
]
function __uniq_Filter (__array_1, __array_2) {
const one_not_in_two = __array_1.filter(function (obj) {
return __array_2.indexOf(obj) == -1
})
const two_not_in_one = __array_2.filter(function (obj) {
return __array_1.indexOf(obj) == -1
})
return one_not_in_two.concat(two_not_in_one)
}
let uniq_filter = __uniq_Filter(ids_exist, ids_new)
console.log('uniq_filter', uniq_filter) // => [ 'abcd', 'efjk', '9999' ]
另一种解决问题的方法
function diffArray(arr1, arr2) {
return arr1.concat(arr2).filter(function (val) {
if (!(arr1.includes(val) && arr2.includes(val)))
return val;
});
}
diffArray([1, 2, 3, 7], [3, 2, 1, 4, 5]); // return [7, 4, 5]
同样,你可以使用箭头函数语法:
const diffArray = (arr1, arr2) => arr1.concat(arr2)
.filter(val => !(arr1.includes(val) && arr2.includes(val)));
diffArray([1, 2, 3, 7], [3, 2, 1, 4, 5]); // return [7, 4, 5]
function array_diff(array1, array2) {
let returnArray = [];
$.each(array1, function(index, value) {
let findStatus = false;
if (Array.isArray(array2)) {
$.each(array2, function(index2, value2) {
if (value == value2) findStatus = true;
});
} else {
if (value == array2) {
findStatus = true;
}
}
if (findStatus == false) {
returnArray.push(value);
}
});
return returnArray;
}
这个怎么样:
Array.prototype.contains = function(needle){
for (var i=0; i<this.length; i++)
if (this[i] == needle) return true;
return false;
}
Array.prototype.diff = function(compare) {
return this.filter(function(elem) {return !compare.contains(elem);})
}
var a = new Array(1,4,7, 9);
var b = new Array(4, 8, 7);
alert(a.diff(b));
这样你就可以用array1。diff(array2)来得到它们的区别算法的时间复杂度很可怕- O(array1。长度(我相信)
function array_diff(a, b) {
let array = [];
for(let i = 0; i <a.length; i++) {
let k = 0;
for( let j = 0; j < b.length; j++) {
if(a[i]!==b[j]) {
k++;
}
if(k===b.length) {
array = array.concat(a[i]);
}
}
if(b.length ===0) {
array = array.concat(a[i]);
}
}
return array;
}