const let var现在常用的是那个

现在常用的是 `const` 和 `let`。`const` 用于声明一个不可变的常量，而 `let` 用于声明一个可变的变量。相比之下，`var` 在ES6之后已经不再被推荐使用，因为它具有函数作用域而不是块级作用域，容易引起变量提升和作用域混乱的问题。所以，在现代的JavaScript开发中，推荐使用`const`和`let`来声明变量。

相关问题

const let var

`const`, `let`, and `var` are all used to declare variables in JavaScript.

`var` was the original way to declare variables in JavaScript. However, it has some issues, such as hoisting and variable scope.

`let` and `const` were introduced in ES6 (ECMAScript 2015) to address these issues.

`let` is used to declare variables that can be reassigned. It has block scope, meaning it is only accessible within the block it is declared in.

`const` is used to declare variables that cannot be reassigned. It also has block scope.

In general, it is recommended to use `let` and `const` instead of `var`, as they have more predictable behavior and help prevent bugs in your code.

var const let

这三个关键字都是用于声明变量的。var是在ES5标准中引入的，let和const则是在ES6标准中引入的。其中，var声明的变量可以被重复赋值，而且存在变量提升的问题。而let和const声明的变量则具有块级作用域，且不能被重复赋值（const声明的只能在声明时赋值一次）。建议在编写JavaScript代码时优先使用let和const来声明变量。