what is the difference between let and const in typescript code example

Example 1: what is the difference between let and const in javascript

The difference is that with const you can only only assign a value to a variable
once, but with let it allows you to reassign after it has been assigned.

Example 2: var vs let vs const typescript

let num1:number = 1; 
    
function letDeclaration() { 
    let num2:number = 2; 

    if (num2 > num1) { 
        let num3: number = 3;
        num3++; 
    } 

    while(num1 < num2) { 
        let num4: number = 4;
        num1++;
    }

    console.log(num1); //OK
    console.log(num2); //OK 
    console.log(num3); //Compiler Error: Cannot find name 'num3'
    console.log(num4); //Compiler Error: Cannot find name 'num4'
}

letDeclaration();