Yahoo! JAPAN

2020/4/2 -var declarations are globally scoped or function scoped while let and const are block scoped. var variables can be updated and re-declared ...

As a rule of thumb, you should use const by default, and only use let when you have to reassign the variable after initialization. You should avoid ...

2022/4/10 -Const acts the same way as let regarding it's scope, but the difference is that it's value can not be redeclared, but the value properties can.

2026/9/4 -The let declaration declares re-assignable, block-scoped local variables, optionally initializing each to a value.

2025/12/6 -var, let and const are used in JavaScript to declare variables, but they differ significantly in their scope, hoisting, and whether they can ...

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 ...

2026/6/25 -When to Use let and const · Use let when you know a variable's value might change later in your code. · Use const for variables that should ...

2015/11/4 -This is why I favor `const` over `let` in ES6. In JavaScript, `const` means that the identifier can't be reassigned. (Not to be confused with ...

2026/4/22 -The three ways to declare a variable in JavaScript - and why modern code uses const by default, let when it has to, and var basically never.