i'm using knockoutjs , here is simplified viewmodel:
var app = function(){
var self = this;
this.index = 0;
myfunction = function(){
//how can i modify index here
self.index = 1;
};
console.log(self.index); // i want to output 1 here , rather than 0
};
new app();
thanks !
Is this related to knockout.js specifically, or are you just trying to sort a plain ECMAScript issue? Any...
It's usually best not to use a function expression where a declaration will do, and constructors should start with a captial letter to let others know that they are constructors.
function App() {
var self = this;
It is unclear why you want to do that. Keeping a reference to this is not common in a constructor.
this.index = 0;
myfunction = function(){
Here's where you get into trouble. When the consructor is called for the first time, the above will create a global variable named myfunction. That probaby isn't what you want to do. A function declaration will stay local, unequivocally. But the function should probaby be on App.prototype anyway.
function myFunction() {
.
//how can i modify index here
self.index = 1;
};
that function will modify the index property, but only if it's called. So what you might do is:
function App(){
this.index = 0; // Each instance will have an index property
}
// All instances will share a myfunction method
App.prototype.myfunction = function() {
this.index = 1;
console.log(this.index);
}
var app = new App();
app.myfunction(); // 1
I'd initialize the function like this:
this.myfunction = function(){
self.index = 1;
};
And then just call it:
var test = new app();
test.myfunction();
console.log(test.index);
Your function is not being called when you initialize it so the code inside isn't being executed.
In your case, however, this should be sufficient (change your code to look similar to this):
myfunction();
console.log(self.index); // i want to output 1 here , rather than 0
