object collection of property and method to to create a model of a something you would recognize from the real world.
the name of method and property called key.
An object cannot have two keys with the same name. This is because keys are used to access their corresponding values.
var person={
firstName:"eman";
secondName:"almkhareez";
age:22;
}; when write this
var x=person; //this not copy from person this means the same object have two name when change in x for example x.age=10 this change reflection on the person.age
The Document Object Model (DOM) specifies how browsers should create a model of an HTML page and how JavaScript can access and update the contents of a web page while it is in the browser window.
this not considered part of html and not part of javascript this have collection of separate of rule .
caching DOM queries
Methods that find elements in the DOM tree are called DOM queries When you need to work with an element more than once , you should use a variable to store the result of this query.
SELECTING AN ELEMENT FROM A NODELIST
the first:The item() method .
the second: and array syntax.
For example, the standard DOM specifies that the querySelectorAll method in the code below must return a list of all the
elements in the document:
const paragraphs = document.querySelectorAll("p"); // paragraphs[0] is the first p element // paragraphs[1] is the second p element, etc. alert(paragraphs[0].nodeName);