Simple testing for variable types

objTests.js

// Can substitute "this" ( / "global" ) for whatever object you want to extend, eg "library.util" or whatever
//
// Creates:
//
// isBoolean( obj )
// isNumber( obj )
// isString( obj )
// isFunction( obj )
// isArray( obj )
// isDate( obj )
// isRegExp( obj )
// isObject( obj )

( function( global ) {
  var types = 'Boolean Number String Function Array Date RegExp Object'.split(' '),
      toStr = Object.prototype.toString,
      i = 0;

  while ( i < types.length ) {
    var type = types[ i ],
        test = '[object ' + type + ']';
        
    global['is' + type ] = ( function( type, test ) {
      return function( obj ) {
        return toStr.call( obj ) === test;
      };

    } )( type, test );

    i++;
  }

}( this ) );