Introduction to JavaScript PDF

SH1804 Introduction to JavaScript I. What is JavaScript?  It is considered as one of the most popular programming languages today.  It is used for webpage functionality,...

SH1804 Introduction to JavaScript I. What is JavaScript?  It is considered as one of the most popular programming languages today.  It is used for webpage functionality, such as interactivity, data processing, and development of purpose-built applications such as mobile and desktop apps, games, and more. II. Adding JavaScript to a Web Page A. Writing Scripts in the Heading  JS uses the tag pair.  JS scripts are usually written within the tag pair of an HTML document. B. Writing Scripts in the Document Body  Alternatively, developers can also write JS scripts within the tag pair in an HTML document via the tag pair.  There is no difference between scripts written in the heading and scripts written in the document body. C. The Tag  An HTML tag pair used to implement JS scripts into HTML documents.  The tags denote that the code within is a JS script.  Can take on two (2) main attributes: type and language. They specify the script’s text type and the programming language, respectively. III. External JavaScript  Scripts that are written and placed in external files.  External files have the file extension.js for JavaScript.  HTML documents can call on these files to execute their script/s using the SRC attribute of the tag.  External JS files don’t use the tag pair as part of their code; developers can directly write their script code on the file as if it’s a normal text file. A. Advantages of External Scripting  Code Separation – It separates HTML and JS code completely by having the script code written in a separate file.  Code Maintenance – Due to being written in two (2) separate files, allows better readability and maintainability of both HTML and JS code.  Faster Page Loading – JS files are cached, speeding up loading times for web pages. IV. Comments in JavaScript  Code in JS that is not “executed”; they are ignored and do not have any effect on the web page.  They are used to describe and explain what the code is doing.  They are written after a double forward slash (//) or between pairs of asterisks and forward slashes ().  Single-line comments used double forward slashes, while the asterisk-forward slash pair is used for multi-line comments. 01 Handout 1 *Property of STI  [email protected] Page 1 of 2  SH1804 References:  SoloLearn. (n.d.) JavaScript Tutorial. Retrieved on April 6, 2018 at https://www.sololearn.com/Course/JavaScript/  SoloLearn. (n.d.) jQuery Tutorial. Retrieved on April 6, 2018 at https://www.sololearn.com/Course/jQuery/ 01 Handout 1 *Property of STI  [email protected] Page 2 of 2