Book Image

Object-Oriented JavaScript - Third Edition

By : Ved Antani, Stoyan STEFANOV
5 (1)
Book Image

Object-Oriented JavaScript - Third Edition

5 (1)
By: Ved Antani, Stoyan STEFANOV

Overview of this book

JavaScript is an object-oriented programming language that is used for website development. Web pages developed today currently follow a paradigm that has three clearly distinguishable parts: content (HTML), presentation (CSS), and behavior (JavaScript). JavaScript is one important pillar in this paradigm, and is responsible for the running of the web pages. This book will take your JavaScript skills to a new level of sophistication and get you prepared for your journey through professional web development. Updated for ES6, this book covers everything you will need to unleash the power of object-oriented programming in JavaScript while building professional web applications. The book begins with the basics of object-oriented programming in JavaScript and then gradually progresses to cover functions, objects, and prototypes, and how these concepts can be used to make your programs cleaner, more maintainable, faster, and compatible with other programs/libraries. By the end of the book, you will have learned how to incorporate object-oriented programming in your web development workflow to build professional JavaScript applications.
Table of Contents (25 chapters)
Object-Oriented JavaScript - Third Edition
Credits
About the Authors
About the Reviewer
www.PacktPub.com
Customer Feedback
Preface
Built-in Functions
Regular Expressions

Appendix B. Built-in Functions

This appendix contains a list of the built-in functions (methods of the global object), discussed in Chapter 3, Functions:

Function

Description

parseInt()

Takes two parameters: an input object and radix; then tries to return an integer representation of the input. Doesn't handle exponents in the input. The default radix is 10 (a decimal number). Returns NaN on failure. Omitting the radix may lead to unexpected results (for example for inputs such as 08), so it's best to always specify it:

    > parseInt('10e+3');   
    10   
    > parseInt('FF');   
    NaN   
    > parseInt('FF', 16);   
    255   

parseFloat()

Takes a parameter and tries to return a floating-point number representation of it. Understands exponents in the input:

    > parseFloat('10e+3');   
    10000   
    > parseFloat('123.456test');   
    123.456   

isNaN()

Abbreviated from "Is Not a Number". Accepts a parameter and returns true if the parameter is not a valid number, false otherwise. Attempts to convert the input to a number first:

    > isNaN(NaN);   
    true   
    > isNaN(123);   
    false   
    > isNaN(parseInt('FF'));   
    true   
    > isNaN(parseInt('FF', 16));   
    false   

isFinite()

Returns true if the input is a number (or can be converted to a number), but if it is not a number Infinity or - Infinity. Returns false for infinity or non-numeric values:

    > isFinite(1e+1000);   
    false   
    > isFinite(-Infinity);   
    false   
    > isFinite("123");   
    true   

encodeURIComponent()

Converts the input into a URL-encoded string. For more details on how URL encoding works, refer to the Wikipedia article at http://en.wikipedia.org/wiki/Url_encode:

    > encodeURIComponent   
    ('http://phpied.com/');   
    "http%3A%2F%2Fphpied.com%2F"   
    > encodeURIComponent   
    ('some script?key=v@lue');   
    "some%20script%3Fkey%3Dv%40lue"   

decodeURIComponent()

Takes an URL-encoded string and decodes it:

    > decodeURIComponent('%20%40%20');   
    " @ "   

encodeURI()

URL-encodes the input, but assumes a full URL is given, so returns a valid URL by not encoding the protocol (for example, http://) and hostname (for example, www.phpied.com):

    > encodeURI('http://phpied.com/');   
    "http://phpied.com/"   
    > encodeURI('some   script?key=v@lue');   
    "some%20script?key=v@lue"   

decodeURI()

Opposite of encodeURI():

    > decodeURI("some%20script?key=v@lue");   
    "some script?key=v@lue"   

eval()

Accepts a string of JavaScript code and executes it. Returns the result of the last expression in the input string.

To be avoided where possible:

    > eval('1 + 2');   
    3   
    > eval('parseInt("123")');   
    123   
    > eval('new Array(1, 2, 3)');   
    [1, 2, 3]   
    > eval('new Array(1, 2, 3); 1 +   2;');   
    3