Will console.log reduce JavaScript execution performance?

Question

Will use of the debugging feature console.log reduce JavaScript execution performance? Will it affect the speed of script execution in production environments?

Answer 1

The performance hit will be minimal, however in older browsers it will cause JavaScript errors if the users browsers console is not open log is not a function of undefined. This means all JavaScript code after the console.log call will not execute.

You can create a wrapper to check if window.console is a valid object, and then call console.log in the wrapper. Something simple like this would work:

window.log = (function(console) {
    var canLog = !!console;
    return function(txt) {
        if(canLog) console.log('log: ' + txt);
    };
})(window.console);

log('my message'); //log: my message

Here is a fiddle: http://jsfiddle.net/enDDV/