I want to add multiple function onchange from javascript to the same input. some thik like this:

this.el = document.getElementById(this.docID);

if(x==y)
{

 this.el.onchange += function(){ // some code }

}
if(a==b)
{

 this.el.onchange += function(){  // some code }

}

I want to add multiple function onchange from javascript to the same input. some thik like this:

this.el = document.getElementById(this.docID);

if(x==y)
{

 this.el.onchange += function(){ // some code }

}
if(a==b)
{

 this.el.onchange += function(){  // some code }

}

• javascript
• html

4 Answers 4

If you want to chain onchange functions, you can do something like this:

this.el = document.getElementById(this.docID);

if(x==y) {
  this.el.onchange = function(){ // some code }
}

if(a==b) {
  var oldOnChange = this.el.onchange;
  this.el.onchange = function(){ 
    // execute previous onchange function
    if(oldOnChange) oldOnChange();

    // some code 
  }
}

Like this you can also decide, whether you want the old onchange function to be executed before or after the new onchange code.

Instead of using the onchange attribute, you should think about using addEventListener and the other DOM2 methods. There are some cross-browser issues which crop up (even when using the onchange attribute) so my remendation is to use a library, such as the jQuery change event observer.

Using jQuery, your code example would look like this:

this.el = document.getElementById(this.docID);

if(x==y) {
    $(this.el).change(function() { /* some code */ });
}
if(a==b) {
    $(this.el).change(function() { /* some code */ });
}

You can't add 2 functions together, that code is wrong. There's only 1 onchange function.

So you could do something like this:

this.el.onchange = function() {   
    if(x==y) {
        // some code
    } else if(a==b) {
        // some other code  
    }  
}

this.el.onchange calls a main function after this calling you do parison and calls other function

this.el = document.getElementById(this.docID);

this.el.onchange += functionx();

functionx() {

if(x==y) {

this.el.onchange += functionY(){ // some code }

} if(a==b) {

this.el.onchange += functionZ(){ // some code }
}

}