(decorator) suspends calls to funtil thereโs sseconds of inactivity (no further calls), then invokes the lastfunction call (previous calls are ignored).
// ๐ debounce.js
// โญ๏ธ decorator: "debounce"
// (suspends 'f' for 's' seconds)
function debounce(f, s) {
// log
console.log(`'${f.name}' has been debounced by ${s} seconds.`)
// โญ๏ธ timer id
let timer;
// wrapper
return function wrapper(...args) {
// โญ๏ธ clear old timer (if it exits)
clearTimeout(timer);
// โญ๏ธ set new timer (in s seconds)
timer = setTimeout(
() => f.apply(this, args),
s * 1000
);
}
}
// export
module.exports = { debounce };
// ๐ index.js
const { debounce } = require('./debounce.js');
// function
function f(...args) {
let t = Date.now(); // current time
let T = (t - t0)/1000; // seconds elapsed from t0
console.log(T.toFixed(2), args);
}
// โญ๏ธ debounce `f` (for 2 seconds)
f = debounce(f, 2);
// โญ๏ธ initial time
let t0 = Date.now();
// โญ๏ธ call the "debounced" `f`
setTimeout(() => f("a"), 0);
setTimeout(() => f("b"), 1.5 * 1000);
setTimeout(() => f("c"), 4.0 * 1000);
// โ โ โ
// a b c
// |----- 1.5 --->|โโโโโโโ 2.0 โโโโโโ>| |โโโโโโโ 2.0 โโโโโโ>|
// (a) (b) (c)
// |....โท....|....โท....|....โท....|....โท....|....โท....|....โท....|
// 0 1 2 3 4 5 6
// log
// ------------------------------------
// 'f' has been debounced by 2 seconds.
//
// 3.50 [ 'b' ]
// 6.00 [ 'c' ]