Useful JS Tricks
BKJang opened this issue Β· comments
JangBongKi commented
π¨ Get Unique Values of an Array
var j = [...new Set([1, 2, 3, 3])]
>> [1, 2, 3]
π¨ Array and Boolean
filter falsy values (0, undefined, null, false, etc.) out of an array.
myArray
.map(item => {
// ...
})
// Get rid of bad values
.filter(Boolean);
π¨ Create Empty Objects
Create empty object __proto__
and the usual hasOwnProperty and other object methods are not exist.
let dict = Object.create(null);
// dict.__proto__ === "undefined"
// No object properties exist until you add them
π¨ Merge Objects
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",
}
*/
π¨ Require Function Parameters
const isRequired = () => { throw new Error('param is required'); };
const hello = (name = isRequired()) => { console.log(`hello ${name}`) };
// This will throw an error because no name is provided
hello();
// This will also throw an error
hello(undefined);
// These are good!
hello(null);
hello('David');
π¨ Destructuring Aliases
const obj = { x: 1 };
// Grabs obj.x as { x }
const { x } = obj;
// Grabs obj.x as { otherName }
const { x: otherName } = obj;
π¨ Get Query String Parameters
// 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"