- 1. Giải quyết phần tử lặp trong mảng bằng cách sử dụng Set.
Code: Select all
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&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&action=edit"
console.log(urlParams.append('active', '1')); // "?post=1234&action=edit&active=1"
- 7. Default Parameters JS
Code: Select all
let a = null
let dict = a || 1
console.log(a) // 1