CODEWITHSUNDEEP
javascript
MightyPork
MightyPork

Reputation: 18891

Wrapper for console.log - Illegal invocation

I'm trying to write a wrapper for console.log.

I found the .apply function in Function prototype, but it's giving me errors:

function _log() {
    if (opts.debug) console.log.apply(this, arguments);
}

opts.debug is a key in my config array.

Error:

Uncaught TypeError: Illegal invocation
    at :2:13
    at Object.InjectedScript._evaluateOn (:905:140)
    at Object.InjectedScript._evaluateAndWrap (:838:34)
    at Object.InjectedScript.evaluate (:694:21)

What's wrong with the way I'm trying to do it? And, how to do it right? Thanks.

Upvotes: 0

Views: 153

Answers (2)

taxicala
taxicala

Reputation: 21779

You are invoking the console.log method in an invalid scope, in order to make it work, you have to invoke it in the console's scope:

function _log() {
    if (opts.debug) console.log.apply(console, arguments);
}

After testing it a couple of times and it seems that @Rob M. is right about his comment. The binding has to be done with the console scope.

Upvotes: 2

Bergi
Bergi

Reputation: 665354

console.log expects to be called as a method of console, i.e with console for the receiver (this argument, first parameter to apply). Currently you're passing this to apply, whatever this is (possibly the global object), it's not the console object. Use

function _log() {
    if (opts.debug) console.log.apply(console, arguments);
//                                    ^^^^^^^
}

Upvotes: 3

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