javascript switch statement explanation code example

Example 1: js switch case

switch(expression) {
  case x:
    // code block
    break;
  case y:
    // code block
    break;
  default:
    // code block
}

Example 2: js convert if/else statement to switch case

var gradeOut = 70;
var totalGrade = 80;

if (gradeOut >= 90)
    gradeOut+= "My letter grade is: A";
  else if (totalGrade < 90 && totalGrade >= 80)
    gradeOut+= "My letter grade is: B";
  else if (totalGrade < 80 && totalGrade >= 70)
    gradeOut+= "My letter grade is: C";
  else if (totalGrade < 70 && totalGrade >= 60)
    gradeOut+= "My letter grade is: D";
  else if (totalGrade < 60)
    gradeOut+= "My letter grade is: F";

//here's the same thing using switch(true). Requires var gradeOut (is currently at top of page
switch(true) {
case gradeOut<60:
    gradeOut= "My letter grade is: F";
    break;
case gradeOut<70:
    gradeOut= "My letter grade is: D";
    break;
case gradeOut<80:
    gradeOut="My letter grade is: C";
    break;
}

Example 3: switch case in js

<html>
   <body>      
      <script type = "text/javascript">
         <!--
            var grade = 'A';
            document.write("Entering switch block<br />");
            switch (grade) {
               case 'A': document.write("Good job<br />");
               case 'B': document.write("Pretty good<br />");
               case 'C': document.write("Passed<br />");
               case 'D': document.write("Not so good<br />");
               case 'F': document.write("Failed<br />");
               default: document.write("Unknown grade<br />")
            }
            document.write("Exiting switch block");
         //-->
      </script>      
      <p>Set the variable to different value and then try...</p>
   </body>
</html>

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