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对象

使用变量作为对象的key​

const name = 'name'

const obj = {
    [name]:'t',
}

深拷贝​

  • 无function, undefined or NaN 值的情况

如果你的对象包含 function, undefined or NaN 值的话，JSON.parse(JSON.stringify(obj)) 就不会有效。因为当你 JSON.stringify 对象的时候，包含 function, undefined or NaN 值的属性会从对象中移除。因此，当你的对象只包含字符串和数字值时，可以使用JSON.parse(JSON.stringify(obj))

let obj = {x: 20, y: {z: 30}};

// Longhand
const makeDeepClone = (obj) => {
  let newObject = {};
  Object.keys(obj).map(key => {
    if(typeof obj[key] === 'object'){
      newObject[key] = makeDeepClone(obj[key]);
    } else {
      newObject[key] = obj[key];
    }
  });
 return newObject;
}
const cloneObj = makeDeepClone(obj);

//Shorthand
const cloneObj = JSON.parse(JSON.stringify(obj));

//Shorthand for single level object
let obj = {x: 20, y: 'hello'};
const cloneObj = {...obj};

对象遍历​

entries​

for (const [key, value] of Object.entries(object1)) {
  console.log(`${key}: ${value}`);
}

values

for (const item of Object.values(object1)) {
  console.log(item);
}

keys

for (const item of Object.keys(object1)) {
  console.log(`key: ${key}`);
}