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
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;
}
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);
}
如果你有两个对象列表
const people = [{name: 'cesar', age: 23}]
const morePeople = [{name: 'cesar', age: 23}, {name: 'kevin', age: 26}, {name: 'pedro', age: 25}]
let result2 = morePeople.filter(person => people.every(person2 => !person2.name.includes(person.name)))
ES2015的函数方法
计算两个数组之间的差值是Set操作之一。这个术语已经表明应该使用本机Set类型,以便提高查找速度。不管怎样,当你计算两个集合之间的差值时,有三种排列:
[+left difference] [-intersection] [-right difference]
[-left difference] [-intersection] [+right difference]
[+left difference] [-intersection] [+right difference]
下面是反映这些排列的功能性解决方案。
离开的区别:
// small, reusable auxiliary functions const apply = f => x => f(x); const flip = f => y => x => f(x) (y); const createSet = xs => new Set(xs); const filter = f => xs => xs.filter(apply(f)); // left difference const differencel = xs => ys => { const zs = createSet(ys); return filter(x => zs.has(x) ? false : true ) (xs); }; // mock data const xs = [1,2,2,3,4,5]; const ys = [0,1,2,3,3,3,6,7,8,9]; // run the computation console.log( differencel(xs) (ys) );
正确的区别:
差异是微不足道的。这与翻转的参数不同。为了方便,你可以写一个函数:const differencer = flip(difference)。这是所有!
对称的区别:
现在我们有了左边和右边,实现对称的差异也变得微不足道:
// small, reusable auxiliary functions const apply = f => x => f(x); const flip = f => y => x => f(x) (y); const concat = y => xs => xs.concat(y); const createSet = xs => new Set(xs); const filter = f => xs => xs.filter(apply(f)); // left difference const differencel = xs => ys => { const zs = createSet(ys); return filter(x => zs.has(x) ? false : true ) (xs); }; // symmetric difference const difference = ys => xs => concat(differencel(xs) (ys)) (flip(differencel) (xs) (ys)); // mock data const xs = [1,2,2,3,4,5]; const ys = [0,1,2,3,3,3,6,7,8,9]; // run the computation console.log( difference(xs) (ys) );
我想这个例子是一个很好的起点,可以让你了解函数式编程的含义:
使用可以以许多不同方式组合在一起的构建块进行编程。
function arrayDiff(a, b) {
return a.concat(b).filter(val => !(b.includes(val)));
//(or) return a.concat(b).filter(val => !(a.includes(val) && b.includes(val)));
}
function diffArray(arr1, arr2) {
const newArr = [];
// arr1 match to arr2
arr1.map((item)=>{
if(arr2.indexOf(item)<0){
console.log(item)
newArr.push(item)
}
})
// arr2 match to arr1
arr2.map((item)=>{
if(arr1.indexOf(item)<0){
newArr.push(item)
}
})
return newArr;
}
差异([1,2,3,5],[1,2,3,4,5])
输出::[4]