what is the and sign in js code example

Example 1: === javascript

// ===	means equal value and equal type
var x = 5

// true
x === 5

// false
x === "5"

Example 2: what does -= mean in JavaScript

/* JavaScript shorthand -=
-= is shorthand to subtract something from a
variable and store the result as that same variable.
*/

// The standard syntax:
var myVar = 5; 
console.log(myVar) // 5
var myVar = myVar - 3;
console.log(myVar) // 2

// The shorthand:
var myVar = 5;
console.log(myVar) // 5
var myVar -= 3;
console.log(myVar) // 2