Yahoo! JAPAN

Variables declared with var are hoisted but initialized with undefined . Variables declared with let and const are also hoisted, but not initialized.

2020/4/2 -var variables can be updated and re-declared within its scope; let variables can be updated but not re-declared; const variables can neither be ...

2026/6/25 -Use let when you know a variable's value might change later in your code. · Use const for variables that should never change once you set them.

2022/4/10 -let is the keyword you should use by default, working with a value you intend to manipulate. Both const and let are scoped, meaning they only ...

2020/8/1 -The three keywords together provide the same fundamental functionality, but differ in the way that they provide it. var and let are reassignable ...

2025/1/4 -Summary: · Use let for things that can change (e.g., scores, counters). · Use const for things that never change (e.g., pi, birth year). · Avoid ...

2025/4/24 -Understand the differences between var, let, and const. Learn scope, use cases, and best practices for cleaner JavaScript code.

2016/12/11 -Basically,. use let if the variable's value will change during the code; use const if it won't and you / your team want to use const in ...

In this post you'll learn the differences between var, let, and const as well as topics like function vs block scope, variable hoisting, and immutability.