/**
* @file fn.js
* @module fn
*/
import { newGUID } from './guid.js';
/**
* Bind (a.k.a proxy or Context). A simple method for changing the context of a function
* It also stores a unique id on the function so it can be easily removed from events.
*
* @param {Mixed} context
* The object to bind as scope.
*
* @param {Function} fn
* The function to be bound to a scope.
*
* @param {number} [uid]
* An optional unique ID for the function to be set
*
* @return {Function}
* The new function that will be bound into the context given
*/
export const bind = function(context, fn, uid) {
// Make sure the function has a unique ID
if (!fn.guid) {
fn.guid = newGUID();
}
// Create the new function that changes the context
const bound = function() {
return fn.apply(context, arguments);
};
// Allow for the ability to individualize this function
// Needed in the case where multiple objects might share the same prototype
// IF both items add an event listener with the same function, then you try to remove just one
// it will remove both because they both have the same guid.
// when using this, you need to use the bind method when you remove the listener as well.
// currently used in text tracks
bound.guid = (uid) ? uid + '_' + fn.guid : fn.guid;
return bound;
};
/**
* Wraps the given function, `fn`, with a new function that only invokes `fn`
* at most once per every `wait` milliseconds.
*
* @param {Function} fn
* The function to be throttled.
*
* @param {Number} wait
* The number of milliseconds by which to throttle.
*
* @return {Function}
*/
export const throttle = function(fn, wait) {
let last = Date.now();
const throttled = function(...args) {
const now = Date.now();
if (now - last >= wait) {
fn(...args);
last = now;
}
};
return throttled;
};