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).
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);
this still resolves to the global object there, no (first example)?
this.getUserAgent is not a functionthis with Browser I get Browser is undefined
Since isIE is being defined as a property before getUserAgent(), you must define it as a function rather than a scalar:
var Browsertest = {
isIE: function() {
return /MSIE (\d+\.\d+)/.test(this.getUserAgent());
},
getUserAgent: function() {
return navigator.userAgent;
}
};
// Call it as a function
console.log(Browsertest.isIE());
You are calling this.getUserAgent in a place where this resolves to the global object.
navigator.userAgent, uppercase variable name for a simple object, etc... I know :(Well first i'd like to point out, please do not use user agent sniffing any more, it is highly frowned upon these days. See This link for more info why UA sniffing is bad
Answer to your question: It will work if you declare the getUserAgent method before the isIE method.
var Browsertest = {
getUserAgent: function() {
return navigator.userAgent;
},
isIE: /MSIE (\d+\.\d+)/.test(this.getUserAgent())
};
This is because:
/MSIE (\d+\.\d+)/.test(this.getUserAgent())
Is immediately executed when it is parsed, because it is an expression, not a function declaration. Therefore it does not know about getUserAgent, because that method has simply not yet been parsed.
But the method getUserAgent is redundant, so you could also write it like this:
var Browsertest = {
isIE: /MSIE (\d+\.\d+)/.test(navigator.userAgent)
};
