Tip JavaScript Hữu Ích

Post by **haihoang** » Fri Dec 11, 2020 9:35 am

1. Giải quyết phần tử lặp trong mảng bằng cách sử dụng Set.

var j = [...new Set([1, 2, 3, 3])]
>> [1, 2, 3]

2. Lọc các falsy values (0, undefined, null, false, vv.) ra khỏi một array

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myArray
    .map(item => {
        // ...
    })
    // Get rid of bad values
    .filter(Boolean);

3. Tạo empty object JS

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let dict = Object.create(null);

4. Merge Objects JS

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const person = { name: 'David Walsh', gender: 'Male' };
const tools = { computer: 'Mac', editor: 'Atom' };
const attributes = { handsomeness: 'Extreme', hair: 'Brown', eyes: 'Blue' };

const summary = {...person, ...tools, ...attributes};
/*
Object {
  "computer": "Mac",
  "editor": "Atom",
  "eyes": "Blue",
  "gender": "Male",
  "hair": "Brown",
  "handsomeness": "Extreme",
  "name": "David Walsh",
}
*/

5. Require Function Parameters JS

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const isRequired = () => { throw new Error('param is required'); };

const hello = (name = isRequired()) => { console.log(`hello ${name}`) };

hello(null);
hello('David');

6. Get Query String Parameters JS

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// Assuming "?post=1234&amp;action=edit"

var urlParams = new URLSearchParams(window.location.search);

console.log(urlParams.has('post')); // true
console.log(urlParams.get('action')); // "edit"
console.log(urlParams.getAll('action')); // ["edit"]
console.log(urlParams.toString()); // "?post=1234&amp;action=edit"
console.log(urlParams.append('active', '1')); // "?post=1234&amp;action=edit&amp;active=1"

7. Default Parameters JS

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let a = null
let dict = a || 1 
console.log(a) // 1

Hai Hoang