Any idea why I have the error Uncaught ReferenceError: hello is not defined ?

function hello() {
    console.log('hello ()');
    setTimeout("hello ()", 1000);
}
setTimeout("hello()", 1000);​

Here is a jsfiddle : /

Any idea why I have the error Uncaught ReferenceError: hello is not defined ?

function hello() {
    console.log('hello ()');
    setTimeout("hello ()", 1000);
}
setTimeout("hello()", 1000);​

Here is a jsfiddle : http://jsfiddle/s9vLk/

• javascript

• 1 Post your code on this site instead of on a different site. Links should be supplemental. – user1106925 Commented Feb 28, 2012 at 2:04

4 Answers 4

The JavaScript code in your demo runs within the 'load' event handler (the option "onLoad" is selected). Therefore, the function hello is not a global function. You have to set the option to "no wrap (body)" or "no wrap (head)". That way, your JavaScript code will be global code.

Live demo: http://jsfiddle/s9vLk/1/

The problem is that you are passing strings to setTimeout() which means code in the string will effectively be evaled and thus isn't running in the scope you think it's running in and so the hello() function isn't found.

If you change the jsfiddle options on the left from "onload" to "no wrap" it works as is because then the function will be global rather than nested inside the onload handler, but a better option is to pass a function reference to setTimeout():

function hello() {
    console.log('hello ()');
    setTimeout(hello, 1000);
}
setTimeout(hello, 1000);

(Note: no parentheses after hello.)

You have a space between hello and the ().

You really should't pass the arguments as a string to setTimeout.

You don't (and shouldn't) need to reference your function name as a string.

function hello() {
    console.log('hello');
    setTimeout(hello, 1000);
}
setTimeout(hello, 1000);

Or better yet

setInterval(function() {
    console.log('hello');
}, 1000);