const let var in javascript code example

Example 1: let vs const

`const` is a signal that the identifier won't be reassigned.

`let` is a signal that the variable may be reassigned, such as a counter in a
loop, or a value swap in an algorithm.

It also signals that the variable will be used only in the block it's defined
in, which is not always the entire containing function.

Example 2: var let const javascript

Const vs Let vs Var

const pi = 3.14

pi = 1 
cannot do this becuase with const you cannot change the value

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Let --> is block level 

for(let i = 0; i < 3; i++) {
console.log(i) --> it will console here
}
console.log(i) ---> Not here


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Var is for variables available to the entire function 


for(var j = 0; j < 3; j++) {
console.log(j) --> it will console here
}
console.log(j) ---> it will console here

Example 3: let in javascript

The let statement declares a block scope local variable, optionally initializing it to a value.

let x = 1;

if (x === 1) {
  let x = 2;

  console.log(x);
  // expected output: 2
}

console.log(x);
// expected output: 1

Example 4: const let var

var greeter;
    console.log(greeter); // greeter is undefined
    greeter = "say hello"