tips.js

// Destructure into multiple variables
const obj = { val: 1 };
const { val: a, val: b, val } = obj;

console.log(a); // -> 1
console.log(b); // -> 1
console.log(val); // ->



// Chaining catch in Promise
const somePromise = async () => Promise.reject('error');
somePromise()
    .then(e => {
        //
    })
    .catch(e => {
        throw new Error('error happened');
    })
    .catch(e => {
        console.log('hi ' + e); // hi Error
    });


// Multiple handlers for Promise
async function add(a, b) {
    return a + b;
}
const promise = add(1, 2);
promise.then(e => `Result 1: ${e}`);
promise.then(e => `Result 2: ${e}`);
// -> Result 1: 3
// -> Result 2: 3



// Mixed promise handler liky try catch
async function someFunction() {
    const res = await somePromise().catch(err => {
        /* handle */
    });
}



// Advanced default params  
function test({ val = -1 } = {}) {
    console.log(val);
}
test(); // -> -1
test({}); // -> -1
test({ val: 123 }); // -> 12


// Generate compact numbers
const formatter = Intl.NumberFormat('en',{ notation: 'compact' });
formatter.format('123'); // -> 123
formatter.format('1234'); // -> 1.2K
formatter.format('1235678'); // -> 1.2M
formatter.format('1235678901'); // -> 1.2B


//Default parameters previously declared
function test(x, y, z = x + y) {
    console.log(z);
}
test(1, 1, 1); // -> 1
test(1, 1); // -> 2



// Additional arguments to setTimeout()
function callback(value) {
    console.log(value);
}
setTimeout(callback, 1000, 5);
// -> Prints '5' after 1 second