1 index.js

var x = 12,
    y = 6,
    firstName = "Larbi",
    lastName = "Ishak",
    name = firstName + lastName;
document.getElementById("test").innerHTML = name;
// you must write the code in the begining of the line 
// to do an inline comment use this // 
/* and to do a big comment use "/*" */ 
if(x>= 10){ document.write("<p><i><b>successful</i></b></p>")}
else{ document.write("<p><i><b>failled</i></b></p>")}
if(x!= 20){ document.write("<p><i><b>True</i></b></p>")}
if(x= 2*y){console.log("hhhhh")}// this will be shown in the console