Javascript: change variable inside a function?

Question

How to change an variable inside a function? I trying to archive an simply toggle function based on one preassigned value. Here the code and here http://jsfiddle.net/StartStep/jLQyx/

<p onclick="testit()">CLick</p>
<p id="value">Value</p>   


var valuediv = document.getElementById("value");

function testit() {
    if (c == 1) {
        var c = 1;
        valuediv.innerHTML = c
    } else {
        var c = 0;
        valuediv.innerHTML = c
    }
}

if c == 1 why are you then assigning c = 1?

David Thomas
– David Thomas

2014-04-16 19:35:44 +00:00
Commented Apr 16, 2014 at 19:35 — David Thomas
– David Thomas, Commented Apr 16, 2014 at 19:35

WASasquatch · Accepted Answer · 2014-04-16 19:43:17Z

3

Have a look at how JavaScript uses Global Variables here.

var valuediv = document.getElementById("value");
var c = 1;

function testit() {
    if(c === 1) 
    {
        c = 0; 
        valuediv.innerHTML = c
    } else {
        c = 1; 
        valuediv.innerHTML = c
    }
}

This fixes your code. You were creating new "c" variables in your if/else blocks due to prefixing them with "var".

Fiddle: http://jsfiddle.net/jLQyx/2/

edited Apr 16, 2014 at 19:43

WASasquatch

1,0443 gold badges11 silver badges19 bronze badges

answered Apr 16, 2014 at 19:35

Wes Copeland

3611 silver badge9 bronze badges

Sign up to request clarification or add additional context in comments.

2 Comments

adihaosd62as Over a year ago

Uh, ok ahahah sorry for my dumbiness also thanks to all the other replies

Wes Copeland Over a year ago

Gotta start somewhere :)

Venkata Krishna · Accepted Answer · 2014-04-16 19:34:54Z

1

Remove var keyword and write c = 1 & c = 0. You're re-creating variable c inside the function instead of updating the global c variable.

var valuediv = document.getElementById("value");
var c = 1;

function testit() {
    if (c == 1) {
        c = 0;
        valuediv.innerHTML = c;
    } else {
        c = 1;
        valuediv.innerHTML = c;
    }
}

http://jsfiddle.net/jLQyx/1/

answered Apr 16, 2014 at 19:34

Venkata Krishna

15.2k5 gold badges45 silver badges57 bronze badges

Comments

Oriol · Accepted Answer · 2014-04-16 19:38:17Z

1

No need to use conditionals:

var valuediv = document.getElementById("value"),
    c = 1;
function testit() {
    c = +!c;
    valuediv.innerHTML = c
}

Demo

answered Apr 16, 2014 at 19:38

Oriol

291k71 gold badges459 silver badges535 bronze badges

3 Comments

adihaosd62as Over a year ago

Nice thing but i must use itto compare that value and execute other code with if/else... no just print the value :D Thanks to you too

Oriol Over a year ago

@AgeLonglife OK, but try to place identical statements in if and else outside the conditional, if possible.

adihaosd62as Over a year ago

but if I use "case/if" it would be something different

Collectives™ on Stack Overflow

Javascript: change variable inside a function?

3 Answers 3

2 Comments

Comments

3 Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

3 Answers 3

2 Comments

Comments

3 Comments

Your Answer

Sign up or log in

Post as a guest

Related