Call javascript function from chrome developer console [duplicate]

Question

Very simple script:

function foo(){
    return "bar"
}

console.log( foo() );

console:

> bar // sanity test that proves everything's working
> foo(); // this guy is key!
> ReferenceError: foo is not defined

How should I call foo(); for debugging and experimentation purposes?

Is this not a practise? I love using IRB / Rails Console to verify my ruby code and want to do the same with JavaScript

http://jsfiddle.net/m2muL/

Answer 1

The problem is that your foo function is not part of the global scope. The console essentially has access to everything that window does. As a result, if it is undefined there, then it is undefined in the console. For example, this could be an example of foo not being available in the console.

(function(){
   function foo(){
     return "bar";
   } 
   console.log(foo()); //"bar"
})()

console.log(foo()); //ReferenceError: foo is not defined

Find a way to locate where this method is exposed. If it is inside of an object or method, make sure to reference that from your console.

var foobar = {
 foo: function(){ return "bar" ;}
};

console.log(foobar.foo()); //"bar"

If you cannot reference foo, then you cannot call it.

Answer 2

You're trying to do this in JSFiddle, which is "hiding" your javascript away from your console. It's not really in scope for you to execute. It's not working there like you are assuming it will...

If you created a simple HTML file and stuck your javascript in there between tags, you wouldn't have a problem running "foo()" in console.

Create test.html and put this inside:

<script>
function foo(){
    return "bar"
}
console.log( foo() );
</script>