var ob = function(){
};
ob.prototype.func = function(){
};
var t = function(){
this.p=0;
this.function1(){
}
var a=new ob();
a.func=function(){//overrides the func
//hope to access this.p this.function1
}
};
is it possible to make a can access this.p this.function1 ？
Your comment welcome
You need to keep a reference to this from inside t if you want to access it within a.func. Try the following:
var t = function(){
var this_t = this; // Use this_t to access this.p and this.function1 inside a
this.p=0;
this.function1 = function(){
}
var a=new ob();
a.func = function(){//overrides the func
this_t.p = 1;
this_t.function1();
}
};
Related
I am trying to get two objects from the same class definition. However they seem to share the same attribute. What can i do?
http://jsfiddle.net/dagod/nuam8dks/2/
myclass = function() {
this.data.push(Math.random(1000));
};
myclass.prototype.data = [];
a = new myclass();
b = new myclass();
console.log(a.data);
console.log(b.data); //same as a.data
I've just been doing this for something else!
myclass = function() {
this.data = [];
};
Now you can access it my simply doing myclass.data =
Personally this is how i'd do it:
var MyNameSpace = {
SomeFunction: function() {
Some code
};
this.somevariable = somevalue;
};
Then you can go myNameSpace.myfunction() or myNameSpace.myVar = Value
See the comment from elclanrs.
var Myclass = function() {
this.data = [];
this.data.push(Math.random(1000));
};
You need to declare your member variable inside the constructor instead of making them part of the prototype. oop in javascript can be ugly and unintuitive. (Thats why there are so many oop libraries out there for javascript)
Using ds.oop
ds.make.class({
type: 'MyClass',
constructor: function(x){
this.a = x;
}
});
var c1 = new MyClass(1);
var c2 = new MyClass(2);
console.log( c1.a ); // output: 1
console.log( c2.a ); // output: 2
You can get the desired results as follows:
myclass = function() {
this.data = Math.random(1000);
};
//myclass.prototype.data = [];
var a = new myclass();
var b = new myclass();
jsfiddle
Look my problem:
I have a class that look like this:
var els=[];
var base = function(){
this.config = {}
}
var X1 = function(){
}
X1.prototype = new base();
X1.prototype.indexme = function(i){
this.config.index = i;
}
X1.prototype.add = function(){
var i = els.push(this)
this.indexme(i)
}
var teste = new X1();
teste.add();
var teste2 = new X1();
teste2.add();
var teste3 = new X1();
teste3.add();
console.log(els)
Why this.config.index is overwritten to another instances?
I expected that teste have config.index = 1; teste2 config.index= 2 and teste3 config.index=3
Thanks
All instances of X1 share the same prototype, which is an instance of base with a config property. Thus, all instances of X1 share the same config property. You can move the line this.config = {}; to the X1 constructor or you can define an init() function in base that assigns this.config for each object and call init() from the X1 constructor.
I have two objects of the same type.
function myObject(){
this.a = 1;
this.b = 1;
function changeA(){//some code};
function changeB(){//some code};
}
var obj1 = new myObject();
var obj2 = new myObject();
How can I make a call to obj2.changeB() from external code, another function or another object (e.g. obj1) ?
obj2.changeB() doesn't exist.
You need to assign a property on your object, not create a local variable:
this.changeB = function() { ... };
Just create a properties in you object like:
function myObject(){
this.a = 1;
this.b = 1;
this.functionA = function changeA(){//some code
alert('im 1');
};
this.functionb = function changeB(){//some code
alert('im 2');};
}
and call the function obj2.functionb();
LIVE DEMO
You have to do something like that:
var myObject = function(){
var protectedValue1 = ‘variable’;
var protectedValue2 = ‘variable’;
var changeA = function(){
alert(protectedValue);
}
var changeB = function(){
alert(protectedValue);
}
}
var object1 = new myObject();
var object2 = new myObject();
//
object2.changeB();
I am getting has no method error
here is the sample code
var snake = function(){
this.initialize = function(){
// initalize
};
this.start = function() {
this.initialize();
};
};
var s = new snake();
var startButton = document.getElementByID("start");
startButton.addEventListener('click',s.start,false);
So when I click start button I am getting
Uncaught TypeError: Object # has no method 'initialize'
how can i fix this
Try
startButtons.addEventListener('click', function() { s.start() }, false);
The this in the function is going to be the input unless you use bind
Because of this. Use a private variable(snk) to ensure you are accessing the snake:
var snake = function(){
var snk = this;
this.initialize = function(){
// initalize
};
this.start = function() {
snk.initialize();
};
};
var s = new snake();
var startButton = document.getElementByID("start");
startButton.addEventListener('click',s.start,false);
I have a batch of Web Audio API nodes that look like the code below. I want to abstract this into a simple constructor but I'm having trouble. I'm not sure what I'm doing wrong. The end result should look something like
function filterTemplate(name,freqVal){
this.name = context.createBiquadFilter();
this.name.type = 5;
this.name.gain.value = null;
this.name.Q.value = 1;
this.name.frequency.value = this.freqVal; // freqVal is here
}
When I call the function:
var filter = new filterTemplate("theName",200); //Uncaught TypeError: Cannot call method 'createBiquadFilter' of undefined
I changed the method to look like this and the error is removed
this.name = function(){return context.createBiquadFilter()};
but then I get another error for the various property values
//Uncaught TypeError: Cannot set property 'value' of undefined
I'm really just confused as to the proper way to create a vanilla constructor using built in browser methods and properties.
I want to abstract the code below into looking something like the code above
filter1 = context.createBiquadFilter();
filter1.type = 5;
filter1.gain.value = null;
filter1.Q.value = 1;
filter1.frequency.value = 80; // Changes
filter2 = context.createBiquadFilter();
filter2.type = 5;
filter2.gain.value = 0;
filter2.Q.value = 1;
filter2.frequency.value = 240; // Changes
filter3 = context.createBiquadFilter();
filter3.type = 5;
filter3.gain.value = 0;
filter3.Q.value = 1;
filter3.frequency.value = 750; // Changes
filter4 = context.createBiquadFilter();
filter4.type = 5;
filter4.gain.value = 0;
filter4.Q.value = 1;
filter4.frequency.value = 2200; // Changes
filter5 = context.createBiquadFilter();
filter5.type = 5;
filter5.gain.value = 0;
filter5.Q.value = 1;
filter5.frequency.value = 6000; // Changes
The builder pattern is very nice for this situation. Especially when you can set a lot of properties.
http://jsfiddle.net/yw8Fm/
You can create a simple FilterTemplate class like this.
function FilterTemplate(builder) {
this.context = builder._context;
this.context.type = builder._type;
this.context.gain.value = builder._gainValue;
this.context.Q.value = builder._qValue;
this.context.frequency.value = builder._frequencyValue;
}
It takes a builder object as constructor argument. Here is the Builder.
FilterTemplate.Builder = function () {
this._context = context.createBiquadFilter();
this._type = 5;
this._gainValue = null;
this._qValue = 1;
this._frequencyValue = 80;
this.context = function (val) {
this._context = val; return this;
};
this.type = function (val) {
this._type = val; return this;
};
this.gainValue = function (val) {
this._gainValue = val; return this;
};
this.qValue = function (val) {
this._qValue = val; return this;
};
this.frequencyValue = function (val) {
this._frequencyValue = val; return this;
};
};
You can further extend this example as you like.
Now you can create FilterTemplates with ease.
var filter1 = new FilterTemplate(
(new FilterTemplate.Builder()).frequencyValue(80)
);
var filter2 = new FilterTemplate(
(new FilterTemplate.Builder()).frequencyValue(80).qValue(2)
);
Your problem is with the scope of your context variable.
var filter = new filterTemplate("theName",200); //Uncaught TypeError: Cannot call method 'createBiquadFilter' of undefined
... means that the context variable isn't available from where you're trying to reach it (which is within the filterTemplate constructor). When you do...
this.name = function(){return context.createBiquadFilter()};
... you're assigning the function to this.name instead, and it won't try to access the context until the function is run, and thus the error is removed. What happens instead is that you don't have a filter in this.name, but rather a function, and a function doesn't have a gain property and therefore you get an error when you try to set this.name.gain.value.
What you should look for is where you define the context, and make sure it's possible to access that variable from within filterTemplate.