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Public properties for Objects in Javascript

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This function allows an object's property names to be read by using an index. The properties can be accessed like: someobject.propertyNames[0] or someobject.propertyValues[0]. But you first have to make the object's properties available by calling someobject.makePublic(['name1','name2','name3',...,'nameN']). The array in the makePublic function is an array of the names of the properties you'd like to make available. Perhaps you're only interested in ['foo','bar']. This is useful for situations where you don't explicitly know if an object carries all properties, but you have an array of all the possible properties available.

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  1. /*	Makes the properties you pass in an array publicly available
  2. 	to access with an index: foo.propertyNames[0];	*/
  3. Object.prototype.makePublic=function(array){
  4. 	var j=0;this.propertyNames=[];this.propertyValues=[];
  5. 	for(var i=0;i<array.length;++i){
  6. 		if(this[array[i]]!==undefined){
  7. 			this.propertyNames.push(array[i]);
  8. 			this.propertyValues.push(this[array[i]]);
  9. 			++j;
  10. 		}
  11. 	}
  12. 	var r=j?j:false;
  13. 	return r;
  14. };
  15.  
  16. /*	Example:
  17. 	//Creating some 'attributes' in an Object called 'a'.
  18. var a={href:"http://example.com",rel:"me",title:"mypage"};
  19.  
  20. 	//Making only the object's 'href' attribute available, and assigning the length to a variable.
  21. var l=a.makePublic(['href']);
  22.  
  23. 	//Alerting the first property name publicly available, along with its value.:
  24. alert(a.propertyNames[0]+"= "+a.propertyValues[0]);
  25. */

URL: http://rolandog.com/archives/2006/07/18/konstructor

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