How to make JavaScript yourself

Learn how to write JavaScript from scratch with a step-by-step example. See how to create a functioning program with variables, functions and more.

Building a Basic JavaScript Program

Creating a JavaScript program from scratch can be daunting. It can seem like a lot of work, but with a few basic steps, you can make your own JavaScript program.

First, you need to create a new file by opening a text editor and writing the following code:

/* This is a comment in JavaScript */

function myFunction() {
  console.log("Hello World!");
}

myFunction();

Here, we have created a new function called myFunction. This function is going to print out “Hello World!” to the console when it is called. The /* This is a comment in JavaScript */ bit is a comment that we have added to explain what the code does. Comments are not necessary for the code to run, but they can help you remember what the code does.

Next, we need to save our file. We can save it with a .js extension, which tells us that this is a JavaScript file. We can now open the file in a web browser. When we open the file, the browser will run the code and print out “Hello World!” to the console.

Now that we have a basic understanding of how JavaScript works, let’s create a more complex program. We can start by creating a variable called myName. We can set the value of this variable to our name:

let myName = "John";

Now, let’s create a function that will print out a greeting to the console:

function greeting() {
  console.log("Hello, my name is " + myName);
}

greeting();

This function will print out “Hello, my name is John” to the console. We can also create an array of names and loop through them to print out a greeting for each one:

let names = ["John", "Jane", "Jill"];

for (let i = 0; i < names.length; i++) {
  console.log("Hello, my name is " + names[i]);
}

Here, we have created an array of names and used a for loop to print out a greeting for each one. This loop will print out “Hello, my name is John”, “Hello, my name is Jane”, and “Hello, my name is Jill” to the console.

We have now created a basic JavaScript program. We can use this program to create more complex programs and add features to it. With a few basic steps, you can create your own JavaScript program.