仅在事件触发时调用函数

Question

I have the following function:

format : function(){
   //function body
   if(condition){
       //execute this condition only on focus event 
   }
}

This function is being called on page load and on the focus of an input element. I have a condition within this function that I would like to be called only when this function is called manually from the focus event and not on page load. Is there a way to achieve this?

There are cases sometimes when the 'condition' in the if statement is true on page load as well. Any help will be appreciated. Thanks in advance.

Answer 1

Separate into two functions:

format: function() {
    //Do stuff for focus
}
onload: function() {
    //Do stuff for onload
    this.format();
}

Answer 2

You can just check for the presence of an event parameter:

format: function(event) {
    if (event) {
        // called form an event
    } else {
        // called manually (without a parameter)
    }
}

For further robustness, check the event.type parameter - it'll contain the name of the event that fired.

Answer 3

Just use event parameter.

format : function(e){
   //function body
   if(e && e.type == 'focus'){
       //execute this condition only on focus event 
   }
}

Demo: http://jsfiddle.net/mbL5ohwr/

Answer 4

you can just was an argument when calling manually on focus and check for no of argument like with special keyword "arguments", when you call it on page load without an argument then length will be zero else it wont be zero , so condition will be true for focus functionality only

format : function(){

 if(arguments.length){
   //execute this condition only on focus event 
 }
 }

Answer 5

You can check whether the element has focus, using for example this === document.activeElement or $(this).is(':focus') . If the function is fired through the focus event, these will return true and if they're called from the onload event, these will return false .

I hope this helped you!

Answer 6

just thought to share: This is what worked for me from the solutions provided to me, thanks for it:

format : function(e){
 //function body
 if(e && e.type == 'focus'){
   //execute this condition only on focus event 
 }
}

Just an FYI, we do not explicitly need to pass the event param, it can be as simple as this:

format : function(){
 //function body
 if(e && e.type == 'focus'){
    //execute this condition only on focus event 
 }
}

e will by default have the reference of the event by which it was caused. Thanks for all of the input.