9个JavaScript日常开发小技巧

let start = 1900, end = 2000;
[...new Array(end + 1).keys()].slice(start);
// [ 1900, 1901, ..., 2000]
// 还有这种方式，但对于很的范围就不太稳定

Array.from({ length: end - start + 1 }, (_, i) => start + i);

const parts = {
 first: [0, 2],
 second: [1, 3],
}

["Hello", "World", "JS", "Tricks"].slice(...parts.second)
// ["World", "JS"]

const elementsHeight = [...document.body.children].map(
 el => el.getBoundingClientRect().y
);
Math.max(...elementsHeight);
// 474

const numbers = [100, 100, -1000, 2000, -3000, 40000];
Math.min(...numbers);
// -3000

const arrays = [[10], 50, [100, [2000, 3000, [40000]]]]

arrays.flat(Infinity)
// [ 10, 50, 100, 2000, 3000, 40000 ]

const found = [{ name: "Alex" }].find(i => i.name === 'Jim')

console.log(found.name)
// TypeError: Cannot read property 'name' of undefined

const found = [{ name: "Alex" }].find(i => i.name === 'Jim') || {}

console.log(found.name)
// undefined

const makeList = (raw) =>
 raw
  .join()
  .trim()
  .split("\n")
  .map((s, i) => `${i + 1}. ${s}`)
  .join("\n");

makeList`
Hello, World
Hello, World
`;
// 1. Hello,World
// 2. World,World

let a = "hello"
let b = "world"

// 错误的方式
a = b
b = a
// { a: 'world', b: 'world' }

// 正确的做法
[a, b] = [b, a]
// { a: 'world', b: 'hello' }

// 错误的做法
["a", "z", "ä"].sort((a, b) => a - b);
// ['a', 'z', 'ä']

// 正确的做法
["a", "z", "ä"].sort((a, b) => a.localeCompare(b));
// [ 'a', 'ä', 'z' ]

const password = "hackme";
password.substr(-3).padStart(password.length, "*");
// ***kme