Title here
Summary here
Switch statements express conditionals across many branches.
Here’s a basic switch.
let i = 2;
console.log("Write " + i + " as ");
switch (i) {
case 1:
console.log("one");
break;
case 2:
console.log("two");
break;
case 3:
console.log("three");
break;
}
You can use commas to separate multiple expressions in the same case
statement. We use the optional default
case in this example as well.
let day = new Date().getDay();
switch (day) {
case 6:
case 0:
console.log("It's the weekend");
break;
default:
console.log("It's a weekday");
break;
}
switch
without an expression is an alternate way to express if/else logic. Here we also show how the case
expressions can be non-constants.
let hour = new Date().getHours();
switch (true) {
case hour < 12:
console.log("It's before noon");
break;
default:
console.log("It's after noon");
break;
}
A type switch compares types instead of values. You can use this to discover the type of a value in JavaScript. In this example, the type of the variable is logged.
function whatAmI(i) {
switch (typeof i) {
case "boolean":
console.log("I'm a bool");
break;
case "number":
console.log("I'm an int");
break;
default:
console.log(`Don't know type ${typeof i}`);
break;
}
}
whatAmI(true);
whatAmI(1);
whatAmI("hey");
To run the code, copy it into an .js
file and execute it using node
.
$ node switch.js
Write 2 as
two
It's a weekday
It's after noon
I'm a bool
I'm an int
Don't know type string