JavaScript Cheat Sheet
If - Else⇵
if ((age >= 14) && (age < 19)) { // logical condition
status = "Eligible."; // executed if condition is true
} else { // else block is optional
status = "Not eligible."; // executed if condition is false
}
Switch Statement
switch (new Date().getDay()) { // input is current day
case 6: // if (day == 6)
text = "Saturday";
break;
case 0: // if (day == 0)
text = "Sunday";
break;
default: // else...
text = "Whatever";
}
Basics➤
On page script
<script type="text/javascript">
</script>
Include external JS file
<script src="filename.js"></script>
Delay - 1 second timeout
setTimeout(function () {
}, 1000);
Functions
function addNumbers(a, b) {
return a + b; ;
}
x = addNumbers(1, 2);
Edit DOM element
document.getElementById("elementID").innerHTML = "Hello World!";
Output
console.log(a); // write to the browser console
document.write(a); // write to the HTML
alert(a); // output in an alert box
confirm("Really?"); // yes/no dialog, returns true/false depending on user click
prompt("Your age?","0"); // input dialog. Second argument is the initial value
Comments
/* Multi line
comment */
// One line
