javascript lesson 8 very important

contructor can be thought of as a template.

For retrieving property values , we have two ways, dot notation and bracket notation

bracket notation has an advantage where we can use variable which store property names as well.

ex :
var somobj = { propname : "propval"};
var p = "propname";

somobj[p];             // this also means somobj["propname"]  , hence this is the advantage.


** sometimes we need to know the type of variable we are using, it can be 'number', 'string','function' or 'object'.

so to find this , we have a function to know this, 'typeof()'
ex :

var a = { b : "dfd"};
console.log(typeof(a));        // o/p is object

****** All objects have a useful function, which tells if an object has a certain property or not, that is 'hasOwnProperty'
ex:

return somobj.hasOwnProperty('name') ;    // returns true or false, if it has that property then true.


** for in loop can be used to print all the property names.
we can also use this to print the property values if we use bracket notation.

ex :
var somobj = { type : "indie" }

for ( var prop in somobj){
     console.log(prop);                    // print the name of property, i.e, o/p is type
     console.log(somobj[prop]);      // print the value of property