17个你不知道的实用javascript技巧！

let number = {

  one: 1,

  two: 2,

};

let key = Object.keys(numbers); // key = [ 'one', 'two' ]

let value = Object.values(numbers);  // value = [ 1, 2 ]

let entry = Object.entries(numbers); // entry = [['one' : 1], ['two' : 2]]

if (docs) {

    goToDocs();

}

docs && goToDocs()

if(a!=123) // before // 一般开发者

if(a^123) // after // B格比较高的

const age = {

   Rahul: 20, 

   max: 16

};

// 方案1：先得 key 在遍历 key

const keys = Object.keys(age);

keys.forEach(key => age[key]++);

console.log(age); // { Rahul: 21, max: 16 }

// 方案2 - `for...in` 循环

for(let key in age){

   age[key]++;

}

console.log(age); // { Rahul: 22, max: 18 }

cosnt obj = {

  name: "前端小智",

  age: 16,

  address: "厦门",

  profession: "前端开发",

};

console.log(Object.keys(obj)); // name, age, address, profession

const arr = [1, 2, 3];

console.log(typeof arr); // object

console.log(Array.isArray(arr)); // true

const size = 5;

const defaultValue = 0;

const arr = Array(size).fill(defaultValue);

console.log(arr); // [0, 0, 0, 0, 0]

// 双等号 - 将两个操作数转换为相同类型,再比较

console.log(0 == 'o'); // true

// 三等号 - 不转换为相同类型

console.log(0 === '0'); // false

function downloadData(url, resourceId, searchTest, pageNo, limit) {}

downloadData(...); // need to remember the order

function downloadData(

{ url, resourceId, searchTest, pageNo, limit } = {}

) {}

downloadData(

  { resourceId: 2, url: "/posts", searchText: "WebDev" }

);

const fn = (x = 'default value') => console.log(x);

fn(undefined); // default value

fn(); // default value

fn(null); // null