I am troubleshooting a slider problem at the moment, however, I don't know javascript that well, I have isolated the .js file that is responsible for the slider functioning, there is a destroy function that I would like to fire off, the code looks like this
(function ($) {
$.pixelentity = $.pixelentity || {version: '1.0.0'};
$.pixelentity.peBackgroundSlider = {
conf: {
api: false,
wait: false
},
paused: false
};
function PeBackgroundSlider(target, conf) {
...
function destroy() {
prevColor = currentColor = currentBW = jwindow = jthis = undefined;
target.data("peBackgroundSlider", null);
target = undefined;
}
}
How would I fire off the destroy function in this scenario?
You can't as it is right now.
To call it you must "export" it as follows:
function PeBackgroundSlider(target, conf) {
...
function destroy() {
prevColor = currentColor = currentBW = jwindow = jthis = undefined;
target.data("peBackgroundSlider", null);
target = undefined;
}
return { "destroy": destroy };
}
From the caller:
var ret = PeBackgroundSlider();
Now you can do:
ret.destroy();
Or, more concise:
return destroy;
And:
innerDestroy = PeBackgroundSlider();
And finally:
innerDestroy();
Related
I have this object that carries some functions. At some point, I would like to hold an event and call this object within that event, but only if you call this object using this, is there any way to call it without this?
I haven't tried anything yet, because I couldn't find anything to help.
const cantaVideoModal = {
click: null,
target: null,
urlVideo: null,
config: function (c) {
this.click = c.click;
this.target = c.target;
this.urlVideo = c.urlVideo;
this.init();
},
init: function () {
this.click = (this.click) ? document.querySelector(this.click) : null;
this.target = (this.target) ? document.querySelector(this.target) : null;
let btnCloseVideo = document.querySelector('[data-close-modal]');
if(btnCloseVideo){
btnCloseVideo.addEventListener('click', function(){
//call modalAction object here using this
})
}
},
modalAction: function (act) {
let elementClick = this.click;
let elementtarget = this.target;
if (elementClick) {
elementClick.addEventListener('click', function (e) {
e.preventDefault();
if (elementtarget) {
if(act === "toggle")
elementtarget.classList.toggle('in');
if(act === "show")
elementtarget.classList.add('in');
if(act === "hide")
elementtarget.classList.remove('in');
}
})
}
}
}
The reason you cannot use this is because you are in a function inside a addEventListener. I'm not sure why, but you can create a new object that refer to the current object, which can be used inside the annonymous functon. For more information on why you can't use this inside a addEventListener see this answer
const cantaVideoModal = {
click: null,
target: null,
urlVideo: null,
config: function (c) {
this.click = c.click;
this.target = c.target;
this.urlVideo = c.urlVideo;
this.init();
},
init: function () {
this.click = (this.click) ? document.querySelector(this.click) : null;
this.target = (this.target) ? document.querySelector(this.target) : null;
let btnCloseVideo = document.querySelector('[data-close-modal]');
if(btnCloseVideo){
// we create a new variable that refer to the current content.
var self = this
btnCloseVideo.addEventListener('click', function() {
//call modalAction object here using self.
self.modalAction(/* some parameters */);
})
}
},
modalAction: function (act) {
let elementClick = this.click;
let elementtarget = this.target;
if (elementClick) {
elementClick.addEventListener('click', function (e) {
e.preventDefault();
if (elementtarget) {
if(act === "toggle")
elementtarget.classList.toggle('in');
if(act === "show")
elementtarget.classList.add('in');
if(act === "hide")
elementtarget.classList.remove('in');
}
})
}
}
}
P.S. I tried using an arrow function but couldn't get the code to work properly.
This is an evolution of a question I asked more than a year ago: How to create methods with a loop in jquery/javascript
I've a code that is shared with other co-workers so it's better if it changes not much. It goes like this:
var scriptList = {
components : [
'all'
],
modules : [
'one',
'two',
'three'
]
}
function core() {
var scope = this;
var promises = [];
jQuery.each(scriptList, function(key, value) {
jQuery.each(value, function (index, name) {
var hookValue = 'hook_'+name,
stringValue = 'string_'+name,
argsValue = 'args_'+name;
scope[name] = function(callback){
window[hookValue] = jQuery('.js-'+name),
window[stringValue] = 'js-'+name;
window[argsValue] = arguments;
loadAndUse(window[hookValue],key+'/'+name,callback);
}
if(key === 'modules'){
scope[name]();
}
});
});
jQuery.when.apply(jQuery, promises).then(function() {
window.executeReady = true;
});
}
ui = new core();
ui.exec = methodLoader;
ui.exec();
This code works fine, because I can use the various method I added with ui.one - ui.two and so on and is also logged in the console if I do console.log(ui).
Before this code gets fired tho, I have now another block of code inside the HTML page, which create a method (always of the ui object) called exec:
window.executeReady = false;
var ui = {},
scriptToBeLoaded = [];
var methodLoader = function(){
var scope = this;
this.exec = function(module, callback){
scriptToBeLoaded.push({
'module' : module,
'callback' : callback
});
if(module === undefined){
console.warn('This module does not exists. Please check the scriptList.');
} else {
function waitForList($context, $variable, $callback) {
if ($context[$variable]) {
$callback();
} else {
Object.defineProperty($context, $variable, {
configurable: true,
enumerable: true,
writeable: true,
get: function() {
return this['_' + $variable];
},
set: function(val) {
this['_' + $variable] = val;
$callback();
}
});
}
}
waitForList(window, 'executeReady', function(){
for (var i = 0; i < scriptToBeLoaded.length; i++) {
ui[scriptToBeLoaded[i].module](scriptToBeLoaded[i].callback);
}
scriptToBeLoaded = [];
});
}
};
};
ui = new methodLoader();
Because of this block of code, when I console.log(ui); I see only the exec method and all of the other methods are gone. Although, the method I create in the core() function are executed correctly, but not present in the ui object.
I would like to edit the code in the HTML Page to have the ui object with exec (which is create on the html side) and the other method (that are created in the js file) all inside the ui object.
How can I achieve that?
You can add new methods to existing object like this. Or you can use jQuery.extend() to merge two object.
var ui = ui || {},
scriptToBeLoaded = [];
ui.exec = function(module, callback){
scriptToBeLoaded.push({
'module' : module,
'callback' : callback
});
if(module === undefined){
console.warn('This module does not exists. Please check the scriptList.');
} else {
function waitForList($context, $variable, $callback) {
if ($context[$variable]) {
$callback();
} else {
Object.defineProperty($context, $variable, {
configurable: true,
enumerable: true,
writeable: true,
get: function() {
return this['_' + $variable];
},
set: function(val) {
this['_' + $variable] = val;
$callback();
}
});
}
}
waitForList(window, 'executeReady', function(){
for (var i = 0; i < scriptToBeLoaded.length; i++) {
ui[scriptToBeLoaded[i].module](scriptToBeLoaded[i].callback);
}
scriptToBeLoaded = [];
});
}
};
Lets say I have a javascript object with the the following
var Settings = function () {
this.timelimit = 0;
this.locked = false;
this.expires = null;
this.age = null;
};
And then I set some get/set functions like:
Settings.prototype = {
getAllAges: function () {
return self.age;
},
getTimeLimit: function () {
return self.timelimit;
},
load: function() {
data_from_local_storage = LoadLocalStorage();
}
}
In data_from_local_storage I have JSON variables that match the above variables (timelimit, locked etc .. )
Issue is, the object var settings_ref = Settings() have all these 4 variables - but also have these 3 functions assigned in settings_ref - due to this OO behavior I need to write inside the load() function:
this.timelimit = data_from_local_storage.timelimit
this.age = data_from_local_storage.age
this.locked = data_from_local_storage.locked
Because if I'll write
this = data_from_local_storage it will destroy my object.
So how can I avoid writing all these variables one-by-one ?
w/o a for loop inside a function
in this example are just 4 but there are much much more and I cannot write it everywhere everytime
I'm looking for some .update() function like in Python or something ..
Any quick shortcut that someone know ?
You can use Object.assign() in ES2015:
load: function() {
Object.assign(this, LoadLocalStorage());
}
It's apparently not supported yet in IE, but there's a polyfill on the MDN page:
if (typeof Object.assign != 'function') {
(function () {
Object.assign = function (target) {
'use strict';
// We must check against these specific cases.
if (target === undefined || target === null) {
throw new TypeError('Cannot convert undefined or null to object');
}
var output = Object(target);
for (var index = 1; index < arguments.length; index++) {
var source = arguments[index];
if (source !== undefined && source !== null) {
for (var nextKey in source) {
if (source.hasOwnProperty(nextKey)) {
output[nextKey] = source[nextKey];
}
}
}
}
return output;
};
})();
}
(Personally I would use Object.defineProperty() to add the method, but that's verbatim from MDN.)
(edit though I guess if you don't have Object.assign() you may not have Object.defineProperty() either :)
If you store the data inside another object literal, it makes persisting things to localstorage and back a lot easier.. Here is an example..
//pretend local storage loader
function LoadLocalStorage() {
return {
timelimit: 100,
locked: true,
expires: new Date(),
age:40
}
}
var Settings = function () {
this.data = {
timelimit: 0,
locked: false,
expires: null,
age:null
}
};
Settings.prototype = {
getAllAges: function () {
return this.data.age;
},
getTimeLimit: function () {
return this.data.timelimit;
},
load: function() {
this.data = LoadLocalStorage();
}
}
var settings = new Settings;
console.log('Age before our load');
console.log(settings.getAllAges());
settings.load();
console.log('Age after our load');
console.log(settings.getAllAges());
Recently I came across a simple Command pattern implementation in JavaScript that uses function as an object instead of pure object to define functionality:
var CommandManager = (function() {
function CommandManager() {}
CommandManager.executed = [];
CommandManager.unexecuted = [];
CommandManager.execute = function execute(cmd) {
cmd.execute();
CommandManager.executed.push(cmd);
};
CommandManager.undo = function undo() {
var cmd1 = CommandManager.executed.pop();
if (cmd1 !== undefined){
if (cmd1.unexecute !== undefined){
cmd1.unexecute();
}
CommandManager.unexecuted.push(cmd1);
}
};
CommandManager.redo = function redo() {
var cmd2 = CommandManager.unexecuted.pop();
if (cmd2 === undefined){
cmd2 = CommandManager.executed.pop();
CommandManager.executed.push(cmd2);
CommandManager.executed.push(cmd2);
}
if (cmd2 !== undefined){
cmd2.execute();
CommandManager.executed.push(cmd2);
}
};
return CommandManager;
})();
and the usage:
CommandManager.execute({
execute: function(){
// do something
},
unexecute: function(){
// undo something
}
});
//call unexecute of prev. command
CommandManager.undo();
//call execute of prev. command
CommandManager.redo();
My question would be, is there any advantages in defining CommandManager function this way, instead of directly defining properties on object literal and assigning it back to var CommandManager
The only use for that would be that you have a function that does absolutely nothing:
CommandManager(); // does nothing, returns undefined
Other than that, you can just as well write the code as an object literal and use this to avoid it being dependant on its own name:
var CommandManager = {
executed: [],
unexecuted: [],
execute: function execute(cmd) {
cmd.execute();
this.executed.push(cmd);
},
undo: function undo() {
var cmd1 = this.executed.pop();
if (cmd1 !== undefined){
if (cmd1.unexecute !== undefined){
cmd1.unexecute();
}
this.unexecuted.push(cmd1);
}
},
redo: function redo() {
var cmd2 = this.unexecuted.pop();
if (cmd2 === undefined){
cmd2 = this.executed.pop();
this.executed.push(cmd2);
this.executed.push(cmd2);
}
if (cmd2 !== undefined){
cmd2.execute();
this.executed.push(cmd2);
}
}
}
I'm trying to make a state machine but it's not working out. I've got this code so far:
function makeStateMachine() {
this.stateConstructors = new Object();
this.currState = {
update : function(e) {
// Nothing to do here
},
exit : function() {
// Nothing to declare
}
};
this.nextState = null;
var that = this;
this.update = new function(e) {
that.currState.update(e);
that.changeState();
};
this.setNextState = new function(targetState) {
that.nextState = targetState;
};
this.addState = new function(constructor, stateName) {
that.stateConstructors[stateName] = constructor;
};
this.changeState = new function() {
if (that.nextState != null) {
that.currState.exit();
that.currState = new that.stateConstructors[that.nextState]();
that.nextState = null;
}
};
}
When I try to run it firebug displays this error: "TypeError: that.changeState is not a function" at the line in the update function. When I uncomment the changeState() line it starts whining about the EaselJS library being incorrect (which I know is correct, because it works for other projects of mine). Can somebody help me out here? It probably something very simple (just like always) but I just can't spot the error. I can post the rest of the code if you guys like but I don't think it's relevant.
Thanks in advance!
You should be putting those functions in the prototype. You also should not be using = new function(...; just use = function(.... Finally, you don't need that. Try this code:
function makeStateMachine() {
this.stateConstructors = {};
this.currState = {
update : function(e) {
// Nothing to do here
},
exit : function() {
// Nothing to declare
}
};
this.nextState = null;
}
makeStateMachine.prototype.update = function(e) {
this.currState.update(e);
this.changeState();
};
makeStateMachine.prototype.setNextState = function(targetState) {
this.nextState = targetState;
};
makeStateMachine.prototype.addState = function(constructor, stateName) {
this.stateConstructors[stateName] = constructor;
};
makeStateMachine.prototype.changeState = function() {
if (this.nextState != null) {
this.currState.exit();
this.currState = new this.stateConstructors[this.nextState]();
this.nextState = null;
}
};