javascript - Why is `function() {{` legal in JS? -


this question has answer here:

i saw js of form:

function f(x) {{ return x + 1; }}

to amazement, syntactically legal , works fine. @ first thought c-style anonymous scopes, not introduce new scope:

function f(x) {{ var y = x + 1; } return y;} // no error

why js accept these superfluous brackets? how interpreted/what mean?

{} denotes block, or "group", of code. unless paired if statement doesn't useful. scope var determined functions in javascript, not blocks.

the new let in es6 scopes blocks.


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