Question

I am writing a little class and I don’t get it why this doesn’t work:

var Browsertest = {

    isIE: /MSIE (\d+\.\d+)/.test(this.getUserAgent()),

    getUserAgent: function() {
        return navigator.userAgent;
    }

};

console.log(Browsertest.isIE);

I get the error that getUserAgent() doesn’t exists/is available (in IE9 and other browsers).

Answer 1

You’re calling the getUserAgent function before it is defined. When using object literals, instance members need to be defined before they are used.

Two alternatives…

One:

var Browsertest = {
    getUserAgent: function() {
        return navigator.userAgent;
    },

    isIE: function() { return /MSIE (\d+\.\d+)/.test(this.getUserAgent()); }
};

console.log(Browsertest.isIE());

Two:

var Browsertest = new function() {
    var that = this;

    this.getUserAgent = function() {
        return navigator.userAgent;
    };

    this.isIE = /MSIE (\d+\.\d+)/.test(that.getUserAgent());
};

console.log(Browsertest.isIE);