# Grammar and types — Variable hoisting

> var-declared variables are hoisted, meaning you can refer to the variable anywhere in its scope, even if its declaration isn't reached yet.

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## Knowledge

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var-declared variables are hoisted, meaning you can refer to the variable anywhere in its scope, even if its declaration isn't reached yet. You can see var declarations as being "lifted" to the top of its function or global scope. However, if you access a variable before it's declared, the value is always undefined, because only its _declaration_ and _default initialization (with undefined)_ is hoisted, but not its _value assignment_.

The above examples will be interpreted the same as

Because of hoisting, all var statements in a function should be placed as near to the top of the function as possible. This best practice increases the clarity of the code.

Whether let and const are hoisted is a matter of definition debate. Referencing the variable in the block before the variable declaration always results in a {{jsxref("ReferenceError")}}, because the variable is in a "temporal dead zone" from the start of the block until the declaration is processed.

Unlike var declarations, which only hoist the declaration but not its value, function declarations are hoisted entirely — you can safely call the function anywhere in its scope. See the hoisting glossary entry for more discussion.

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