Summary

WHAT IS AN OBJECT?

Objects: group together a set of variables and functions to create a model of a something you would recognize from the real world. In an object, variables and functions take on new names.

In JavaScript:

• Variables have a name and you can assign them a value of a string, number, or Boolean.
• Arrays have a name and a group of values. (Each item in an array is a name/value pair because it has an index number and a value.)
• Named functions have a name and value that is a set of statements to run if the function is called.
• Objects consist of a set of name/value pairs (but the names are referred to as keys).

Example var hotel = { name: ‘Quay’, rooms : 40, booked: 25, checkAvailability: function() { return this.rooms - this.booked; } } ; JAVASCRIPT var elName = document .getElementByld(‘hotelName’); elName.textContent =hotel .name; var elRooms = document.getElementByid{‘rooms’); elRooms .textContent = hotel .checkAvailability();

Summay

Document object model

• The browser represents the page using a DOM tree. DOM trees have four types of nodes: document nodes, element nodes, attribute nodes, and text nodes.
• You can select element nodes by their id or cl ass attributes, by tag name, or using CSS selector syntax.
• Whenever a DOM query can return more than one node, it will always return a Nadel i st.
• From an element node, you can access and update its content using properties such as textContent and i nnerHTML or using DOM manipulation techniques.
• An element node can contain multiple text nodes and child elements that are siblings of each other.
• In older browsers, implementation of the DOM is inconsistent (and is a popular reason for using jQuery). Browsers offer tools for viewing the DOM tree .