Develop Reference

Namespace With New Instance On Each Call

I'm trying to create something similar to d3(ex: d3.select()) but much more simple and I need to have a new instance each time I call the namespace function. Is this possible and/or am I approaching this wrong?
var dom = new function () {
var Element = null;
this.select = function (query) {
Element = document.querySelector(query);
return this;
};
this.append = function (elem) {
Element.append(elem);
return this;
};
};
Desired use
var bodyelement = dom.select("body");
var p = dom.select("p");

You need to run some code each time you use the dom object. So if the dom object was a function, you could call it to get a new instance.
var dom = function () {
var Element = null;
var newdom = {};
newdom.select = function (query) {
Element = document.querySelector(query);
return this;
};
newdom.append = function (elem) {
Element.append(elem);
return this;
};
return newdom;
};
console.log(dom() === dom(), "(false means the instances are different)");

var dom = new function () {
var Element = null;
this.select = function (query) {
Element = document.querySelector(query);
return this;
};
this.append = function (elem) {
Element.append(elem);
return this;
};
// add a way of accessing the resulting Element
this.element = function() { return Element; }
};
console.log(dom.select("body").element());
console.log(dom.select("p").element());
<p>blah</p>

Use Javascript Object to Angular Service

I am trying to add functions to a JS Object which will be used as a singleton service.
angular
.module('app.steps')
.factory('createStepsService', createStepsService);
createStepsService.$inject = [];
/* #ngInject */
function createStepsService() {
var steps;
var service = {
newSteps: function (current_step, total_steps) {
if (!steps) {
return new Steps(current_step, total_steps);
}
}
};
return service;
function Steps(current_step, total_steps) {
this.c_step = current_step;
this.t_step = total_steps;
}
Steps.prototype = {
addSteps: function (num) {
this.c_step += num;
},
setLastStep: function () {
this.lastStep = this.c_step = this.t_step;
}
};
}
When I run this line from the controller, I am not able to access
addSteps / setLastStep methods.
vm.createStepsService = createStepsService.newSteps(1, 3);
Why I don't see these methods? Were they created?
Thanks.

Your steps.prototype code is never ran.
This is because it appears after the return.
Change the order of your code to this:
/* #ngInject */
function createStepsService() {
var steps;
function Steps(current_step, total_steps) {
this.c_step = current_step;
this.t_step = total_steps;
}
Steps.prototype = {
addSteps: function (num) {
this.c_step += num;
},
setLastStep: function () {
this.lastStep = this.c_step = this.t_step;
}
};
var service = {
newSteps: function (current_step, total_steps) {
if (!steps) {
return new Steps(current_step, total_steps);
}
}
};
return service;
}
The reason that you can have a function declared before a return is because of JavaScript variable and function hoisting.

Your problem is that you are creating Steps.prototype after a return statement, so it will never be read.

In AngularJS, services are singletons objects that are instantiated only once per app.
And the factory() method is a quick way to create and configure a service.
It provides the function's return value i.e. Need to create an object, add properties to it, then it will return that same object.
For ex:
angular
.module('myApp',[])
.factory("createStepService", function(){
var stepServiceObj = {};
var c_step = 0;
var t_steps = 0;
var last_step = 0;
stepServiceObj.setCurrentStep = function(current_step){
c_step = current_step;
console.log('c_step1: ',c_step);
};
stepServiceObj.getCurrentStep = function(){
return c_step;
};
stepServiceObj.setTotalStep = function(total_steps){
t_steps = total_steps;
};
stepServiceObj.getTotalStep = function(){
return t_steps;
};
stepServiceObj.setLastStep = function(){
last_step = c_step = t_step;
};
stepServiceObj.getLastStep = function(){
return last_step;
};
stepServiceObj.addSteps = function(num){
return c_step += num;
};
return stepServiceObj;
});

A Javascript function which creates an object which calls the function itself

I am trying to make an angular service that returns a new object.
That's fine and good and works. new MakeRoll() creates an instance. But self.add, near the end also calls new MakeRoll() and that doesn't create an instance when I call add like I think it should.
I'm probably doing this all wrong but I haven't been able to figure it out.
var services = angular.module('services', []);
services.factory('Roll', [function() {
var MakeRoll = function () {
var self = {};
self.rolls = [];
self.add = function(number, sizeOfDice, add) {
var newRoll = {};
newRoll.number = number || 1;
newRoll.sizeOfDice = sizeOfDice || 6;
newRoll.add = add || 0;
newRoll.rollDice = function() {
var result = 0;
var results=[];
for (var i = 0; i < newRoll.number; i++) {
var roll = Math.floor(Math.random() * newRoll.sizeOfDice) + 1;
result += roll;
results.push(roll);
}
newRoll.results = results;
newRoll.result = result;
newRoll.Roll = new MakeRoll();
};
self.rolls.push(newRoll);
return self;
};
self.remove = function(index) {
self.rolls.splice(index, 1);
};
self.get = function(index) {
return self.rolls[index];
};
return self;
};
return new MakeRoll();
}
]);

angular service is designed to be singleton to accomplish some business logic, so don't mix up plain model with angular service. if you want to have more objects, just create a constructor and link it in service to be operated on.
function MakeRoll() {
...
}
angular.module('service', []).factory('Roll', function () {
var rolls = [];
return {
add: add,
remove: remove,
get: get
}
function add() {
// var o = new MakrRoll();
// rolls.push(o);
}
function remove(o) {
// remove o from rolls
}
function get(o) {
// get o from rolls
}
});

How to "new" a returned function in Javascript

I am trying to simulate a namespace feature in Javascript.
var com = {};
com.domain = {};
com.domain.system = {};
com.domain.net = {};
com.domain.net.ip = {};
com.domain.net.ip.tcp = {};
com.domain.net.ip.udp = {};
com.domain.net.ip.ssl = {};
com.domain.util = {};
com.domain.util.timer = {};
com.domain.plugins = {};
com.domain.session = {};
com.domain.io = {};
com.domain.algorithm = {};
com.domain.debug = {};
This is the namespaces declaration. Later I will add functions to these namespaces.
This is my selector function:
For a convenient way to use namespaces, I add a function named $. This function will walk all namespaces in com. If the selected name exists, return the object.
function $ (selector) {
function digger (namespace, selector) {
for (var prop in namespace) {
if (typeof namespace[prop] == "array" || typeof namespace[prop] == "object") {
if (prop == selector) {
return namespace[prop];
}
var dig = digger(namespace[prop], selector);
if (dig != null) {
return dig;
}
} else {
if (prop == selector) {
return namespace[prop];
}
}
}
}
return digger (com, selector);
}
After that, I add a timer to namespace com.doamin.util.
com.domain.util.timer = function () {
this._handle = new InnerObj.SystemTimer(io);
return this;
};
com.domain.util.timer.prototype.expiresFromNow = function (seconds, cbHandler) {
this._handle.ExpiresFromNow (seconds, cbHandler);
};
com.domain.util.timer.prototype.wait = function (seconds, cbHandler) {
this._handle.Wait (seconds, cbHandler);
};
com.domain.util.timer.prototype.expiresAt = function (seconds, cbHandler) {
this._handle.Wait (seconds, cbHandler);
};
com.domain.util.timer.prototype.cancel = function () {
this._handle.Cancel ();
};
Usage:
1. var timer = new com.domain.util.timer (); OK
timer.expiresAt (1, {}); OK
2. var func = $("timer"); OK
var timer = new func (); OK
timer.expiresAt (1, {}); OK
But but but but but
var timer = new $("timer") (); NG
Can anyone tell me why the last new function is not working?

Try var timer = new ($("timer"))();.
Your question is not clear but I guess since $("timer") returns a function, you want a new instance of the result of $("timer") and not a new instance of $().

Losing object reference on lookup in Javascript

I'm working on an extension for Google Chrome and I ran into the following situation:
I'm trying to get all the existing tabs from all the opened windows in the same instance of Google Chrome. I manage to get them and construct an array of objects that contain the relevant data for me.
When I look at the constructed array using console.log (which is saved for future use also) I can see the collection of objects, but I can't reference them (when I try I get undefined).
I tried to save the array outside my object in a container, but nothing changes.
Any idea why the reference to the objects go away when I try to look them up? Thanks.
Here is the code:
(function(window){
//defining a namespace
var example = {
bmarksmaster: (function() {
var bmarksmaster = function() {
return new bmarksmaster.fn.init();
}
bmarksmaster.fn = bmarksmaster.prototype = {
debug: false,
tabs: [],
constructor: bmarksmaster,
init: function() {
return this;
},
windowParser: function(ctx, filter) {
var local = ctx;
var filter = filter;
return function(wObj) {
if((wObj !== null) && (wObj !== undefined)) {
for(var idx in wObj) {
var cw = wObj[idx];
if((cw.tabs !== null) && (cw.tabs !== undefined)) {
var cwtabs = cw.tabs;
for(var tabIdx in cwtabs) {
local.tabs.push(filter(tabIdx, cwtabs[tabIdx]));
}
}
}
}
};
},
getTabs: function() {
var returnData = [];
chrome.windows.getAll(
{
"populate": true
}, this.windowParser(this, function(i, e) {
var data = {};
if(!e.incognito) {
data["title"] = e.title;
data['url'] = e.url;
data['favicon'] = e.favIconUrl || "";
}
return data;
}));
return this.tabs;
},
getTab: function(callback) {
this.getTabs();
for (var tabIdx in this.tabs) {
if(callback(tabIdx, this.tabs[tabIdx])) {
return this.tabs[tabIdx];
}
}
},
getTabsData: function(callback) {
var data = [];
var tabs = [];
tabs = this.getTabs();
console.log(this.tabs[0]);
for (var tabIdx in tabs) {
console.log(tabs[tabIdx]);
var tabData = callback(tabIdx, tabs[tabIdx]);
if(tabData) {
data.push(tabData);
}
}
return data;
},
setDebug: function() {
this.debug = true;
},
resetDebug: function() {
this.debug = false;
}
};
bmarksmaster.fn.init.prototype = bmarksmaster.fn;
return bmarksmaster;
})()
};
window.example = example;
})(window);
//end of bmarksmaster.js file
console.log(example.bmarksmaster().getTabs()); //this works, I can see the array
console.log(example.bmarksmaster().getTabs()[0]); //this doesn't work, I get undefined, never mind the shortcut

I think the logic in your code is wrong. It is a bit convoluted and hard to follow. I would recommend rewriting it a bit to be simpler. Something like this might help get you started. It collects all the windows, putts all the tabs into the tabs var.
var tabs = [];
chrome.windows.getAll({ populate: true}, function(windows) {
var localTabs = windows.reduce(function(a, b){
return a.tabs.concat(b.tabs);
});
tabs = localTabs.filter(function(element){
return !element.incognito;
});
})