Saving JavaScript `console.log` to global variable or file

EDIT 2

Do use a library like loglevel

See the answers below to understand how you can implement something like this by yourself.

original answer:

Do something like:

var myLogs = [];
(function () {
  var log = console.log;
  console.log = function () {
    var args = Array.prototype.slice.call(arguments)
    log.apply(this, args );
    myLogs.push(args);
  };
}());

The gloabl variable myLogs will contain your log data.

You may want to adopt the code to your needs. Maybe you want to make one string out of the args array.

EDIT

If you want to have console.log, console.error, console.warn, console.info and store the log level:

var logData = [];
(function () {
    var log = console.log,
        error = console.error,
        warn = console.warn,
        info = console.info;

    console.log = function () {
        var args = Array.prototype.slice.call(arguments)
        log.apply(this, args );
        logData.push({level: "log", arguments: args});
    };
    console.error = function () {
        var args = Array.prototype.slice.call(arguments)
        error.apply(this, args );
        logData.push({level: "error", arguments: args});
    };
    console.warn = function () {
        var args = Array.prototype.slice.call(arguments)
        warn.apply(this, args );
        logData.push({level: "warn", arguments: args});
    };
    console.info = function () {
        var args = Array.prototype.slice.call(arguments)
        info.apply(this, args );
        logData.push({level: "info", arguments: args});
    };
}());