Object property problem

JavaScript
1

hi all,

i’m buliding an image slider object with the following code:

  1. function imageGalery(index, width){
  2. …
  3. this.isScrolling = false;
  4. …
  5. this.startScroll = function(){
  6. if(this.isScrolling == false){
  7. this.isScrolling = setInterval(‘galery’+index+‘.scroll();’,30);
  8. }
  9. }
  10. this.stopScroll = function(){
  11. clearInterval(this.isScrolling);
  12. this.isScrolling = false;
  13. }
  14. …
  15. img = document.createElement(‘img’);
  16. img.onmouseover = this.startScroll;
  17. img.onmouseout = this.stopScroll;
  18. …
  19. }

the thing is that it start scrolling only on the second time i hover the img…

i’m guessing it’s because the stopScroll method was already launched but i don’t understand why declaring the property isn’t enough.

i have also manged to bypass it by writing “eval(‘galery’+index)” (the object’s name) instead of “this” on line 6. can someone explain?

2

that was quick!
thank u, storing ‘this’ will sure be helpful.
regarding the setInterval, i’ll check myself…

thanx again!

3

this is no longer the same inside the function. The nested function creates a new closure, and therefore creates a new sort of “environment” that has its own this. So to avoid this, you have to make a copy of the original this.

function imageGalery(index, width) {
  this.isScrolling = false;
  var gal = this;
  this.startScroll = function() {
    if (!gal.isScrolling) {
      gal.isScrolling = setInterval('galery'+index+'.scroll();',30);
    }
  }
}

The stuff inside the setInterval looks very suspicious. It looks like you’re making lots of differently named functions that do the same thing. Can’t they all be merged into a single function that takes an argument?