ncatalin
2/23/2018 - 5:00 PM

If Statements & Comparison Operators

Modern JavaScript From The Beginning from Brad Traversy

index.html
content_copyfile_download
<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <meta http-equiv="X-UA-Compatible" content="ie=edge">
  <title>JavaScript Sandbox: Section 2</title>
</head>
<body>
  <h1>JavaScript Sandbox: Section 2</h1>
  
  <script src="app.js"></script>
</body>
</html>
app.js
content_copyfile_download
// if(something){
//   do something
// } else {
//   do something else
// }

const id = 100;

// // EQUAL TO
// if(id == 100){
//   console.log('CORRECT');
// } else {
//   console.log('INCORRECT');
// }

// // NOT EQUAL TO
// if(id != 101){
//   console.log('CORRECT');
// } else {
//   console.log('INCORRECT');
// }

// // EQUAL TO VALUE & TYPE
// if(id === 100){
//   console.log('CORRECT');
// } else {
//   console.log('INCORRECT');
// }

// // EQUAL TO VALUE & TYPE
// if(id !== 100){
//   console.log('CORRECT');
// } else {
//   console.log('INCORRECT');
// }

// Test if undefined
// if(typeof id !== 'undefined'){
//   console.log(`The ID is ${id}`);
// } else {
//   console.log('NO ID');
// }

// GREATER OR LESS THAN
// if(id <= 100){
//   console.log('CORRECT');
// } else {
//   console.log('INCORRECT');
// }

// IF ELSE

const color = 'yellow';

// if(color === 'red'){
//   console.log('Color is red');
// } else if(color === 'blue'){
//   console.log('Color is blue');
// } else {
//   console.log('Color is not red or blue');
// }

// LOGICAL OPERATORS

const name = 'Steve';
const age = 70;

// AND &&
if(age > 0 && age < 12){
  console.log(`${name} is a child`);
} else if(age >= 13 && age <= 19){
  console.log(`${name} is a teenager`);
} else {
  console.log(`${name} is an adult`);
}

// OR ||
if(age < 16 || age > 65){
  console.log(`${name} can not run in race`);
} else {
  console.log(`${name} is registered for the race`);
}

// TERNARY OPERATOR
console.log(id === 100 ? 'CORRECT' : 'INCORRECT');

// WITHOUT BRACES
if(id === 100)
  console.log('CORRECT');
else
  console.log('INCORRECT');

if(id === 100)
  console.log('CORRECT');
else
  console.log('INCORRECT');