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. };
  16. /* Example:
  17. //Creating some 'attributes' in an Object called 'a'.
  18. var a={href:"",rel:"me",title:"mypage"};
  20. //Making only the object's 'href' attribute available, and assigning the length to a variable.
  21. var l=a.makePublic(['href']);
  23. //Alerting the first property name publicly available, along with its value.:
  24. alert(a.propertyNames[0]+"= "+a.propertyValues[0]);
  25. */


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