Here are some commonly used JavaScript string methods:

1. length: Returns the length of a string.

   const str = 'Hello, World!';
   console.log(str.length); // Output: 13​

2. toUpperCase(): Converts a string to uppercase.

   const str = 'Hello, World!';
   console.log(str.toUpperCase()); // Output: HELLO, WORLD!​

3. toLowerCase(): Converts a string to lowercase.

   const str = 'Hello, World!';
   console.log(str.toLowerCase()); // Output: hello, world!​

4. indexOf(): Returns the index of the first occurrence of a specified value in a string.

   const str = 'Hello, World!';
   console.log(str.indexOf('World')); // Output: 7​

5. slice(): Extracts a part of a string and returns a new string.

   const str = 'Hello, World!';
   console.log(str.slice(7)); // Output: World!
   console.log(str.slice(7, 12)); // Output: World​

6. replace(): Searches a string for a specified value, or a regular expression, and returns a new string where the specified values are replaced.

   const str = 'Hello, World!';
   console.log(str.replace('World', 'Universe')); // Output: Hello, Universe!​

7. split(): Splits a string into an array of substrings.

   const str = 'Hello, World!';
   console.log(str.split(',')); // Output: ['Hello', ' World!']​

8. trim(): Removes whitespace from both ends of a string.

   const str = '   Hello, World!   ';
   console.log(str.trim()); // Output: Hello, World!​

These are just a few of the many available JavaScript string methods.

JavaScript events are actions or occurrences that happen in a web page, such as a user clicking a button, a page finishing loading, or a form being submitted. Here are some examples of how to handle events in JavaScript:

1. Handle a button click event:

   var button = document.getElementById('myButton');
   button.addEventListener('click', function() {
     console.log('Button clicked!');
   });​

2. Handle a page load event:

   window.addEventListener('load', function() {
     console.log('Page loaded!');
   });​

3. Handle a form submission event:

   var form = document.getElementById('myForm');
   form.addEventListener('submit', function(event) {
     event.preventDefault();
     console.log('Form submitted!');
   });​

4. Handle a mouse over event:

   var element = document.getElementById('myElement');
   element.addEventListener('mouseover', function() {
     console.log('Mouse over!');
   });​

5. Handle a key press event:

   document.addEventListener('keypress', function(event) {
     console.log('Key pressed: ' + event.key);
   });​

These are just a few examples of the types of events you can handle in JavaScript. There are many more events available, and you can also create your own custom events using the Event interface.

JavaScript statements are used to perform actions and make decisions in a program. Here are some common JavaScript statements:

1. Variable declaration: Used to declare a variable and assign it a value.

   var x = 5;​

2. Conditional statement: Used to execute different code blocks based on a condition.

   if (x > 10) {
     console.log('x is greater than 10');
   } else {
     console.log('x is less than or equal to 10');
   }​

3. Looping statement: Used to execute a block of code multiple times.

   for (var i = 0; i < 10; i++) {
     console.log(i);
   }​

4. Function declaration: Used to define a function that can be called later in the program.

   function add(x, y) {
     return x + y;
   }​

5. Switch statement: Used to execute different code blocks based on the value of a variable.

   switch (day) {
     case 'Monday':
       console.log('Today is Monday');
       break;
     case 'Tuesday':
       console.log('Today is Tuesday');
       break;
     default:
       console.log('Today is not Monday or Tuesday');
   }​

These are just a few examples of the types of statements you can use in JavaScript. There are many more statements available that can help you perform different actions and make decisions in your program.

Chrome extensions are built using web technologies such as HTML, CSS, and JavaScript. Therefore, the code used to develop a Chrome extension is essentially JavaScript code, but with some additional APIs and functionalities provided by the Chrome browser.

A Chrome extension typically consists of a manifest file and one or more JavaScript files. The manifest file defines various properties of the extension, such as its name, version, and permissions required. The JavaScript files contain the logic and functionality of the extension.

In other words, the code used to develop a Chrome extension is JavaScript code, but with some additional APIs and functionalities provided by the Chrome browser.