问题描述
有没有办法让我的代码更简单?
仅供参考,我是初学者,我只学习了一周的 JavaScript。
谢谢!
let array = [1,2,4,591,392,391,5,10,1,20,20];
// from above to [[1,1],[2,2],[20,20],591]
const answer = (arr) => {
arr.sort((a,b) => {
return a - b;
});
let counter = 0;
arr.forEach((num,i) => {
if (arr[i] === arr[i+1]) {
counter++;
} else if (arr[i] !== arr[i + 1] && arr[i] === arr[i-1]) {
arr[i-counter] = arr.slice(i-counter,i + 1);
counter = 0;
}
});
arr.forEach((num,i) => {
while (arr[i][0] && arr[i][0] === arr[i + 1]) {
arr.splice(i + 1,1);
}
});
return arr;
}
const newArray = answer(array);
console.log(newArray);
解决方法
您可以先对它们进行排序,然后再对其进行分组,从而使其更简单。
let array = [1,2,4,591,392,391,5,10,1,20,20],last = null;
const result = array
.sort((a,b) => a - b)
.reduce((acc,curr,index,arr) => {
// Getting the next element in array
const next = arr[index + 1];
if (last && last === curr) acc[acc.length - 1].push(curr);
else if (next && next === curr) acc.push([curr]);
else acc.push(curr);
// Changing the last to the curr
last = curr;
return acc;
},[]);
console.log(result);
使用 Map 对元素进行分组然后按键对 Map 条目进行排序的方法,以免根本不改变原始数组
let array = [1,20];
const answer = (arr) =>{
const m = new Map();
arr.forEach(n => m.set(n,(m.get(n) || []).concat(n)));
return [...m.entries()].sort(([a],[b])=> a-b)
.map(([k,v]) => v.length > 1 ? v : v[0])
}
console.log(answer(array))
另一种选择。首先将每个数字推入对象的相应数组中,然后根据需要将对象转换为结果数组。
let arr = [1,20];
const obj = {},res = [];
for(e of arr) !obj[e] ? obj[e] = [e] : obj[e].push(e);
for(a in obj) obj[a].length === 1 ? res.push(obj[a][0]) : res.push(obj[a]);
console.log(res);