pp-parachute/util/debounce.js

Airdrop JS Applications

var Promise = require('bluebird');
//debounces a function by calling it first then timing out before calling it again
var debounceHead = function (ctx, fn, waitTime) {
    var timeout = null;
    var promise = null;
    var resolve = null;
    return function () {
        promise = promise || new Promise(function(_resolve) {
            resolve = _resolve;
        });
        var args = arguments;
        if (!timeout) {
            timeout = setTimeout(function () {
                timeout = null;
                promise = null;
                resolve = null;
            }, waitTime || 250);
            resolve(fn.apply(ctx, args));
        } else {
            clearTimeout(timeout);
            timeout = setTimeout(function () {
                resolve(fn.apply(ctx, args));
                timeout = null;
                promise = null;
                resolve = null;
            }, waitTime || 250);
        }
        return promise;
    }
};

//debounces a function by waiting for `wait` ms of not being called again before calling fn.
var debounceTail = function (ctx, fn, wait) {
    var timeout = null;
    return function () {
        var context = this, args = arguments;
        var later = function () {
            timeout = null;
            fn.apply(context, args);
        };
        clearTimeout(timeout);
        timeout = setTimeout(later, wait || 250);
    };
};

module.exports = {
    debounceHead: debounceHead,
    debounceTail: debounceTail
};