Order of hoisting in JavaScript

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Functions are hoisted first, then variable declarations, per ECMAScript 5, section 10.5 which specifies how hoisting happens:

We first have step 5 handling function declarations:

For each FunctionDeclaration f in code, in source text order do…

Then step 8 handles var declarations:

For each VariableDeclaration and VariableDeclarationNoIn d in code, in source text order do…

So, functions are given higher priority than var statements, since the later var statements cannot overwrite a previously-handled function declaration.
(Substep 8c enforces the condition “If varAlreadyDeclared is false, then [continue…]” so extant variable bindings are not overwritten.)

You can also see this experimentally:

function f(){}
var f;
console.log(f);

var g;
function g(){}
console.log(g);

Both log calls show the function, not an undefined value.

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