These are some cool Javascript programs:

    Today I made a JS script to create a json file with the KEY, SYN, ANT for the following book:
    A COMPLETE DICTIONARY OF Synonyms and Antonyms, 1898 BY The Rt. Rev. Samuel Fallows, A.M., B.D.
    Script:

    
                             
                                        
                                            const fs = require('fs');
                                            const readline = require('readline');
                                            const fileStream = fs.createReadStream('SYNANT.html');
    
                                            const rl = readline.createInterface({
                                                input: fileStream,
                                                crlfDelay: Infinity 
                                            });
    
                                            let SYNANT = {}
    
                                            let lastKeyIndex = -1, index = -1, Key, Syn, Ant
    
                                            rl.on('line', (line) => {
                                                index += 1
                                                if(line.includes("KEY: ")){
                                                    lastKeyIndex = index
                                                }
                                                if(lastKeyIndex == index){
                                                    Key = generateValue(line)
                                                    Key.replace(/[^a-zA-Z]/g, '')
                                                }else if(lastKeyIndex + 1 == index){
                                                    Syn = generateValue(line)
    
                                                }else if(lastKeyIndex + 2 == index){
                                                    Ant = generateValue(line)
                                                    
                                                    SYNANT[Key] = {SYN : Syn, ANT: Ant}
                                                }
                                            });
    
                                            rl.on('close', () => {
                                                let json = JSON.stringify(SYNANT, null, 4);
                                                fs.writeFile(
                                                    "SYNANT.json",
                                                    json,
                                                    err => {
                                                        if (err) throw err;
                                                    }); 
    
                                                console.log("Done writing");
                                            });
    
                                            function generateValue(line){
                                                let key = ""
                                                let add = false
    
                                                for(let i = 1; i < line.length; i++){
                                                    if(line[i - 1] == " ")
                                                    add = true
                                                    if(line[i] == ".")
                                                        add = false
                                                    if(add)
                                                        key += line[i]
                                                }
                                                return key.trim()
    
                                            }
                                        
                                    
    RESULT

    I'M JAVASCRIPT!
                                        
                                            <!DOCTYPE html>
                                            <html lang="en">
                                            <head>
                                                <meta charset="UTF-8">
                                                <meta name="viewport" content="width=device-width, initial-scale=1.0">
                                                <title>Document</title>
                                            </head>
                                            <body>
                                                I'M JAVASCRIPT
                                            </body>
                                            </html>
                                            <script>
                                                alert("I AM JAVASCRIPT!")
                                            </script>
                                        
                                    
    I'M JAVASCRIPT WITH EXTERNAL
    INDEX.HTML
                                        
                                            <!DOCTYPE html>
                                            <html lang="en">
                                            <head>
                                                <meta charset="UTF-8">
                                                <meta name="viewport" content="width=device-width, initial-scale=1.0">
                                                <title>Document</title>
                                            </head>
                                            <body>
                                                I'M JAVASCRIPT
                                            </body>
                                            </html>
                                            <script src="./index.js">
                                            </script>
                                        
                                    
    INDEX.JS
                                        
                                            alert("I AM JAVASCRIPT")
                                        
                                    
    WORKING WITH LETTERS
                                        
                                            let newName = 'John';
                                            let admin = newName;
                                            console.log(admin)
                                        
                                    
    GIVING THE RIGHT NAME
                                        
                                            // Create a variable with the name of our planet. How would you name such a variable?
                                            let ourPlanet = "Earth";
                                            // Create a variable to store the name of a current visitor to a website. How would you name that variable?
                                            let newVisitor = "John"
                                        
                                    
    UPPERCASE OR CONST?
                                        
                                            // Here we have a constant birthday for the date, and also the age constant.
    
                                            // The age is calculated from birthday using someCode(), which means a function call that we didn’t explain yet (we will soon!), but the details don’t matter here, the point is that age is calculated somehow based on the birthday.
    
                                            // Would it be right to use upper case for birthday? For age? Or even for both?
    
                                            const BIRTHDAY = '18.04.1982'; // make birthday uppercase because it's a known value
    
                                            const AGE = someCode(BIRTHDAY); // make age camelCase because its value is'nt know before execution?
                                        
                                    
    STRING QUOTES
                                        
                                            // What is the output of the script?
                                            let newName = "Ilya";
    
                                            console.log( `hello ${1}` ); // hello 1
    
                                            console.log( `hello ${"name"}` ); // hello name
    
                                            console.log( `hello ${newName}` ); // hello Ilya
    
                                        
                                    
    A SIMLE PAGE!
                                        
                                            let visitor_name = prompt('Pls enter your name sir!');
    
                                            alert(`Your name is ${visitor_name}`); 
                                        
                                    
    THE POSTFIX AND PREFIX FORMS
                                        
                                            let a = 1, b = 1;
    
                                            let c = ++a; 
                                            let d = b++; 
                                            // a = 2, b = 2, c = 2, d = 1
                                            console.log(a, b, c, d)
                                        
                                    
    ASSIGNMENT RESULT
                                        
                                            let a = 2;
    
                                            let x = 1 + (a *= 2);
                                            // a = 4, x = 5
                                            console.log(a, x)
                                        
                                    
    TYPE CONVERSIONS
                                        
                                            console.log("" + 1 + 0); // 10
                                            console.log("" - 1 + 0);  // -1
                                            console.log(true + false); // 1
                                            console.log(6 / "3"); // 2
                                            console.log("2" * "3"); // 6
                                            console.log(4 + 5 + "px"); // 9px
                                            console.log("$" + 4 + 5); // $45
                                            console.log("4" - 2); // 2
                                            console.log("4px" - 2); // Nan
                                            console.log("  -9  " + 5); // -9  5
                                            console.log("  -9  " - 5); // -14
                                            console.log(null + 1); // 1
                                            console.log(undefined + 1); // Nan
                                            console.log(" \t \n" - 2 ); // -2
                                        
                                    
    FIX THE ADDITION
                                        
                                            // Here’s a code that asks the user for two numbers and shows their sum.
    
                                            // It works incorrectly. The output in the example below is 12 (for default prompt values).
                                            
                                            // Why? Fix it. The result should be 3.
                                            
                                            // ORIGINAL CODE:
                                            
                                            let a = prompt("First number?", 1);
                                            let b = prompt("Second number?", 2);
                                            
                                            alert(a + b); // 12
                                            
                                            
                                            // BY USING UNARY PLUS I CAN CONVERT THE STRINGS TO NUMBERS
                                            let a = prompt("First number?", 1);
                                            let b = prompt("Second number?", 2);
                                            
                                            alert(+a + +b); // 12