v8 JavaScript performance implications of const, let, and var?

Question

Regardless of functional differences, does using the new keywords \'let\' and \'const\' have any generalized or specific impact on performance relative to \'var\'?

A

Answer 1

"LET" IS BETTER IN LOOP DECLARATIONS

With a simple test (5 times) in navigator like that:

// WITH VAR
console.time("var-time")
for(var i = 0; i < 500000; i++){}
console.timeEnd("var-time")

The mean time to execute is more than 2.5ms

// WITH LET
console.time("let-time")
for(let i = 0; i < 500000; i++){}
console.timeEnd("let-time")

The mean time to execute is more than 1.5ms

I found that loop time with let is better.