JavaScript | Statements

Difficulty Level : Basic
Last Updated : 25 Mar, 2019

The programming instructions written in a program in a programming language are known as statements.

Order of execution of Statements is the same as they are written.

Semicolons:

Semicolons separate JavaScript statements.

Semicolon marks the end of a statement in javascript.

Example:

<!DOCTYPE html>
<html>
  
<body>
    <h2>Welcome</h2>
  
    <p id="geek"></p>
  
    <script>
        // Statement 1
        var a, b, c;
  
        // Statement 2
        a = 2;
  
        // Statement 3
        b = 3;
  
        // Statement 4
        c = a + b;
  
        document.getElementById(
          "geek").innerHTML =
            "The value of c is " + c + ".";
    </script>
  
</body>
  
</html>

Output:

Multiple statements on one line are allowed if they are separated with a semicolon.
```
a=2;b=3;z=a+b;
```

Code Blocks:
JavaScript statements can be grouped together inside curly brackets. Such groups are known as code blocks. The purpose of grouping is to define statements to be executed together.

Example:JavaScript function

<!DOCTYPE html>
<html>
  
<body>
    <p>Welcome</p>
  
    <button type="button" 
            onclick="myFunction()">
      Click Me!
  </button>
  
    <p id="geek1"></p>
    <p id="geek2"></p>
  
    <script>
        function myFunction() {
            
            document.getElementById(
              "geek1").innerHTML = "Hello";
            
            document.getElementById(
              "geek2").innerHTML = 
              "How are you?";
        }
    </script>
  
</body>
  
</html>

Output:
Before Click:

After Click:

White Space:
- Javascript ignores multiple white spaces.
Javascript would treat following 2 statements as same:
Example:
```
var a="Hello Geek";
var a = "Hello Geek";
```
Line Length and Line Breaks:
Javascript code preferred line length by most programmers is upto 80 characters.
The best place to break a code line in Javascript, if it doesn’t fits, is after an operator.
Example:
```
document.getElementById("geek1").innerHTML =
"Hello Geek!";
```
Keywords:
Keywords are reserved words and cannot be used as variable name.
A Javascript keyword tells about what kind of operation it will perform.
Some commonly used keywords are:
- break: This is used to terminate a loop or switch.
- continue: This is used to skip a particular iteration in a loop and move to next iteration.
- do…. while: In this the statements written within do block are executed till the condition in while is true.
- for: It helps in executing a block of statements till the condition is true.
- function: This keyword is used to declare a function.
- return: This keyword is used to exit a function.
- var: This keyword is used to declare a variable.
- switch: This helps in executing a block of codes depending on different cases.

My Personal Notes

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