JavaScript Syntax

Whitespace and new lines

JavaScript ignores spaces, tabs, and newlines that appear in JavaScript code. You are free to format and indent your programs in a neat and consistent way that makes the code easy to read and understand.

Semicolons

S tatements in JavaScript generally end with a semicolon character, similar to C, C++, and Java. JavaScript, however, allows you to omit this semicolon if each of your statements are placed on a separate line.

• Example 1
  
• 
  
•       varA  = "Learn"
  
•       varB = "JAScript"
  
• 
  
• Example 2
  
• 
  
•       varA  = "Learn" varB = "JAScript"
  
• 
  
• Example 3
  
• 
  
•       varA  = "Learn"; varB = "JAScript";

In the above examples Example 1 and 3 will run while example 2 will generate error.

Case Sensitivity

JavaScript is a case-sensitive language. This means that the language keywords, variables, function names, and any other identifiers must always be typed in consistency.

• Example 4
  
• 
  
•     var myVar = 5;
  
•     var myvar = 10;
  
•     print(myVar);
  
•     print(myvar);
  

        Example 5

       function myFunction(){
         return 5;

• };
  
• 
  
•  function myfunction(){

        return 10;

• };

In the above example myVar and myvar and two different variables and they will print 5 and 10 respectively. In example 5, the two functions are totally different


Comments in JavaScript

JavaScript supports both C-style and C++-style comments.

1. Any text between a // and the end of a line is treated as a comment and is ignored by JavaScript.
2. Any text between the characters /* and */ is treated as a comment. This may span multiple lines.

• Example 6
  
• 
  
• //This is a single line comment
  
• var val = 5;
  
• var name = "Tree";
  
• var combined = val+name;
  
• print(combined);
  
• /*
  
• This
  
• is
  
• a
  
• multiline
  
• comment
  
• */

Outputting strings in JAScript

For android projects
There are many ways to output a string in JAScript. The following are some of the ways you can display a string:-

1. print();
   
2. System.out.println()
   
3. alert();
   
4. popup()
   

For HTML Projects

      1 document.write()
       2 console.log()
       3 element.innerText


Examples

Example 1

• var a = "JAScript";
  
• print(a);
  

To see the output of the example above open menu, then select console.

Example 2

• var System = Packages.java.lang.System;
  
• var a = "JAScript";
  
• System.out.println(a);

Example 2 will also output to console.

Example 3

• var b = "JavaScript";
  
• alert(b);
  

Example 3 will show an alert dialog containing the word JavaScript

Example 4

• var c = "Popup";
  
• popup(c);

Example 4 will show a toast with the content of variable c i.e Popup