When to use JavaScript const? Always declare a variable with const when you know that the value should not be changed. Use const when you declare: A new Array; A new Object; A new …

Mar 19, 2025 · The const declaration declares block-scoped local variables. The value of a constant can't be changed through reassignment using the assignment operator, but if a …

Apr 2, 2020 · 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 updated nor re-declared. They are …

Apr 7, 2025 · var: Declares variables with function or global scope and allows re-declaration and updates within the same scope. let: Declares variables with block scope, allowing updates but …

Jan 20, 2014 · const creates an immutable binding, meaning a const variable identifier is not reassignable. const a = "value1"; You cannot reassign it with. a = "value2"; However, if the …

Sep 25, 2008 · Since ES2015, JavaScript has a notion of const: This will work in pretty much all browsers except IE 8, 9 and 10. Some may also need strict mode enabled. You can use var …

So the usual rules around variable hoisting within a scope -- block-scoped variables (let and const) do not hoist as undefined to the top of their block scope. This means: doSomething() // …

Feb 12, 2025 · The const keyword in JavaScript is a modern way to declare variables, introduced in (ES6). It is used to declare variables whose values need to remain constant throughout the …

Mar 18, 2025 · When learning JavaScript, understanding the difference between let, var, and const is essential. These three keywords are used for variable declaration, but they behave …

Jan 11, 2023 · var and let create variables that can be reassigned another value. const creates "constant" variables that cannot be reassigned another value. developers shouldn't use var …