Switch Case in JavaScript

We have learned about decision-making in JavaScript using if-else statements in our previous article on if-else statements in JavaScript. We have seen in our previous article that we can use the if-else statements to perform actions based on some particular condition. That is if a condition is true then perform some task or else if the condition is false then execute some other task. 

The switch case statement in JavaScript is also used for decision-making purposes. In some cases, using the switch case statement is seen to be more convenient than if-else statements. Consider a situation when we want to test a variable for hundred different values and based on the test we want to execute some task. Using if-else statements for this purpose will be less efficient than switch-case statements and also it will make the code look messy.

The switch case statement is a multiway branch statement. It provides an easy way to dispatch execution to different parts of code based on the value of the expression.

Syntax: 

switch (expression)
{
    case value1:
        statement1;
        break;
    case value2:
        statement2;
        break;
    .
    .
    case valueN:
        statementN;
        break;
    default:
        statementDefault;
}

Explanation: 

• The expression can be of type numbers or strings.
• Duplicate case values are not allowed.
• The default statement is optional. If the expression passed to the switch does not match the value in any case then the statement under default will be executed.
• The break statement is used inside the switch to terminate a statement sequence.
• The break statement is optional. If omitted, execution will continue on into the next case.
• Cases are compared strictly.

Flowchart: 

Example: 

JavaScript

<script type = "text/javascript">

    // JavaScript program to illustrate switch-case
    let i = 9;

    switch (i)
    {
    case 0:
        console.log("i is zero.");
        break;
    case 1:
        console.log("i is one.");
        break;
    case 2:
        console.log("i is two.");
        break;
    default:
        console.log("i is greater than 2.");
    }

</script>

Output: 

i is greater than 2.

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