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KooiInc
KooiInc
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[Edit march 2013] based on progressing insight this is a better method:

Object.prototype.is = function() { var test = arguments.length ? [].slice.call(arguments) : null ,self = this.constructor; return test ? !!(test.filter(function(a){return a === self}).length) : (this.constructor.name || (String(self).match ( /^function\s*([^\s(]+)/im) || [0,'ANONYMOUS_CONSTRUCTOR']) [1] ); } // usage var Some = function(){ /* ... */} ,Other = function(){ /* ... */} ,some = new Some; 2..is(String,Function,RegExp); //=> false 2..is(String,Function,Number,RegExp); //=> true 'hello'.is(String); //=> true 'hello'.is(); //-> String /[a-z]/i.is(); //-> RegExp some.is(); //=> 'ANONYMOUS_CONSTRUCTOR' some.is(Other); //=> false some.is(Some); //=> true // note: you can't use this for NaN (NaN === Number) (+'ab2').is(Number); //=> true

[Edit march 2013] based on progressing insight this is a better method:

Object.prototype.is = function() { var test = arguments.length ? [].slice.call(arguments) : null ,self = this.constructor; return test ? !!(test.filter(function(a){return a === self}).length) : (this.constructor.name || (String(self).match ( /^function\s*([^\s(]+)/im) || [0,'ANONYMOUS_CONSTRUCTOR']) [1] ); } // usage var Some = function(){ /* ... */} ,Other = function(){ /* ... */} ,some = new Some; 2..is(String,Function,RegExp); //=> false 2..is(String,Function,Number,RegExp); //=> true 'hello'.is(String); //=> true 'hello'.is(); //-> String /[a-z]/i.is(); //-> RegExp some.is(); //=> 'ANONYMOUS_CONSTRUCTOR' some.is(Other); //=> false some.is(Some); //=> true // note: you can't use this for NaN (NaN === Number) (+'ab2').is(Number); //=> true
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KooiInc
KooiInc
  • 123.5k
  • 32
  • 145
  • 181

For all types I cooked up an Object prototype function. It may be of use to you

Object.prototype.typof = function(chkType){ var inp = String(this.constructor), customObj = (inp.split(/\({1}/))[0].replace(/^\n/,'').substr(9), regularObj = Object.prototype.toString.apply(this), thisType = regularObj.toLowerCase() .match(new RegExp(customObj.toLowerCase())) ? regularObj : '[object '+customObj+']'; return chkType ? thisType.toLowerCase().match(chkType.toLowerCase()) ? true : false : thisType; }

Now you can check any type like this:

var myDate = new Date().toString(), myRealDate = new Date(); if (myRealDate.typof('Date')) { /* do things */ } alert( myDate.typof() ); //=> String