JavaScript: changing input value using JavaScript?

Question

I'm trying to do a very simple task but for some reason I can't do it.

basically I am using the if statement to change the value of an input field using javascript but it doesn't work!

this is my code:

if (document.getElementById("colour").value == "171515"){
    document.getElementById("colour").value = "db0000";
}

if (document.getElementById("colour").value == "db0000"){
    document.getElementById("colour").value = "171515";
}

and the HTML looks like this:

<input type="text" id="colour" name="colour" class="colour" value="171515"/>

so what i need to do is this:

I launch a page and the input field is on my page with the value of value="171515", and then I press a button and that should change the value of the input field to value="db0000", and then I press the button again, and it should change the value of the input button to value="171515" and I need to do the same steps as many times as I want.

currently, it seems like it gets into a loop action and thats why it doesn't change the value of input field! (correct me if i'm wrong).

any help would be appreciated.

Thanks

EDIT:

The javascript code above is executed like so:

$(params.addPplTrigger).bind('click', function(e){
                    e.preventDefault();

///////// THE CODE ABOBE WILL GO HERE///////////

}

Possibly button events may be the reason how you're executing it? — Just code
– Just code, Commented Dec 1, 2014 at 12:59
It's worth noting that you have two ifs, one changes the value one way, the other changes it back. Use if (condition) {...} else if (condition) {...} or a simple if (condition) {...} else {...}. — David Thomas
– David Thomas, Commented Dec 1, 2014 at 12:59

Shomz · Accepted Answer · 2014-12-01 13:08:33Z

1

You're just missing an else:

if (document.getElementById("colour").value == "171515"){
    document.getElementById("colour").value = "db0000";
}

else if (document.getElementById("colour").value == "db0000"){
    document.getElementById("colour").value = "171515";
}

What happens in your original code

Case 171515:

first if condition evaluates to true, because the value is 171515
value gets changed to db0000
second if condition evalutes to true again, because the value is db0000 now
value gets changed back to 171515

Case db0000:

first if condition gets evaluates to false, because the value is not 171515
the value remains the same
second if condition gets evaluates to true, because the value is db0000
value gets changed to 171515

So, in both cases you'd end up with 171515.

edited Dec 1, 2014 at 13:08

answered Dec 1, 2014 at 13:00

Shomz

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6 Comments

David Thomas Over a year ago

If there's only two possibilities (and one must be true) the else if (condition) can be replaced by a simple else (though not my down-vote).

user3806613 Over a year ago

WORKED. THANKS EVER SO MUCH. I up VOTED THE ANSWER .... I DON'T KNOW WHY SOMEONE DOWNVOTED IT!!!!

Jamiec Over a year ago

Ha well spotted (My initial comment was far too hasty!)

Just code Over a year ago

@DavidThomas well spotted

Shomz Over a year ago

Yeah, I'm really curious at what happens in the brain of those reflex-downvoters at times... You're welcome, hope I helped you understand what was going on.

|

Suchit kumar · Accepted Answer · 2014-12-01 13:04:38Z

0

since you are doing :

if (document.getElementById("colour").value == "171515"){
    document.getElementById("colour").value = "db0000";
}

and then reverse

if (document.getElementById("colour").value == "db0000"){
    document.getElementById("colour").value = "171515";
}

so you are not able to see the change .use else instead of second if.

if (document.getElementById("colour").value == "171515"){
    document.getElementById("colour").value = "db0000";
}else{
    document.getElementById("colour").value = "171515";
}

answered Dec 1, 2014 at 13:04

Suchit kumar

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