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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.

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  1. 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;
  2. 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:

  3. White Space:
    • Javascript ignores multiple white spaces.

    Javascript would treat following 2 statements as same:
    Example:

    var a="Hello Geek";
    var a = "Hello Geek";
    
  4. 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!";
    
  5. 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.



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