Uncaught TypeError: Illegal invocation in javascript

fcortes picture fcortes · Jan 18, 2012 · Viewed 34.8k times · Source

I'm creating a lambda function that executes a second function with a concrete params.This code works in Firefox but not in Chrome, its inspector shows a weird error, Uncaught TypeError: Illegal invocation. What's wrong of my code?

var make = function(callback,params){
    callback(params);
}

make(console.log,'it will be accepted!');

Answer

Paul picture Paul · Jan 18, 2012

The console's log function expects this to refer to the console (internally). Consider this code which replicates your problem:

var x = {};
x.func = function(){
    if(this !== x){
        throw new TypeError('Illegal invocation');
    }
    console.log('Hi!');
};
// Works!
x.func();

var y = x.func;

// Throws error
y();

Here is a (silly) example that will work, since it binds this to console in your make function:

var make = function(callback,params){
    callback.call(console, params);
}

make(console.log,'it will be accepted!');

This will also work

var make = function(callback,params){
    callback(params);
}

make(console.log.bind(console),'it will be accepted!');