what is the use of colon in javascript code example

Example 1: colon in js

document.getElementById("demo").innerHTML = age>18? "True" : "False";

Example 2: colon in js

switch (new Date().getDay()) {
    case 6:
        text = "Today is Saturday";
        break; 
    case 0:
        text = "Today is Sunday";
        break; 
    default: 
        text = "Looking forward to the Weekend";
}