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
您可以使用一个公共对象并计算第一个数组中每个值的频率。对于第二个数组,减少公共对象中的值。然后遍历所有键并添加所有值大于1的键。
常量差值= (a1, a2) => { Var obj = {}; a1。forEach(obj[v] = (obj[v] || 0) + 1); a2。forEach(v => obj[v] = (obj[v] || 0) - 1); 返回对象 . keys (obj) .reduce((r,k) => { If (obj[k] > 0) r = r.concat (Array.from({长度:obj [k]}) .fill (k)); 返回r; }, []); }; const =结果不同([' a ', ' ', ' b ', ' c ', ' d '], [a, b]); console.log(结果);
其他回答
下面是一个稍微修改的版本,它使用Object来存储哈希,可以处理数组中的数字和字符串。
function arrDiff(a, b) {
const hash = {};
a.forEach(n => { hash[n] = n; });
b.forEach(n => {
if (hash[n]) {
delete hash[n];
} else {
hash[n] = n;
}
});
return Object.values(hash);
}
使用http://phrogz.net/JS/ArraySetMath.js你可以:
var array1 = ["test1", "test2","test3", "test4"];
var array2 = ["test1", "test2","test3","test4", "test5", "test6"];
var array3 = array2.subtract( array1 );
// ["test5", "test6"]
var array4 = array1.exclusion( array2 );
// ["test5", "test6"]
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);
var arrayDifference = function(arr1, arr2){
if(arr1 && arr1.length){
if(arr2 && arr2.length > 0){
for (var i=0, itemIndex; i<arr2.length; i++){
itemIndex = arr1.indexOf(arr2[i]);
if(itemIndex !== -1){
arr1.splice(itemIndex, 1);
}
}
}
return arr1;
}
return [];
};
arrayDifference([1,2,3,4,5], [1,5,6]);
类似于Ian Grainger的解决方案(但在打字稿中):
function findDiffs(arrayOne: string[], arrayTwo: string[]) {
let onlyInArrayOne = []
let onlyInArrayTwo = []
let share = []
let [arrayOneCopy, arrayTwoCopy] = [[...arrayOne], [...arrayTwo]]
arrayOneCopy.sort(); arrayTwoCopy.sort()
while (arrayOneCopy.length !== 0 && arrayTwoCopy.length !== 0) {
if (arrayOneCopy[0] == arrayTwoCopy[0]) {
share.push(arrayOneCopy[0])
arrayOneCopy.splice(0, 1)
arrayTwoCopy.splice(0, 1)
}
if (arrayOneCopy[0] < arrayTwoCopy[0]) {
onlyInArrayOne.push(arrayOneCopy[0])
arrayOneCopy.splice(0, 1)
}
if (arrayOneCopy[0] > arrayTwoCopy[0]) {
onlyInArrayTwo.push(arrayTwoCopy[0])
arrayTwoCopy.splice(0, 1)
}
}
onlyInArrayTwo = onlyInArrayTwo.concat(arrayTwoCopy)
onlyInArrayOne = onlyInArrayOne.concat(arrayOneCopy)
return {
onlyInArrayOne,
onlyInArrayTwo,
share,
diff: onlyInArrayOne.concat(onlyInArrayTwo)
}
}
// arrayOne: [ 'a', 'b', 'c', 'm', 'y' ]
// arrayTwo: [ 'c', 'b', 'f', 'h' ]
//
// Results:
// {
// onlyInArrayOne: [ 'a', 'm', 'y' ],
// onlyInArrayTwo: [ 'f', 'h' ],
// share: [ 'b', 'c' ],
// diff: [ 'a', 'm', 'y', 'f', 'h' ]
// }