®参考文档: JavaScript reference (like:Statements Block ...)
https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference
A block statement (or compound statement in other languages) is used to group zero or more statements. The block is delimited by a pair of curly brackets and may optionally be labelled
:
Syntax
[label:] { statement_1; statement_2; ... statement_n; }
statement_1
,statement_2
,statement_n
- Statements grouped within the block statement.
- label
- An optional
label
for visual identification or as a target forbreak
.