为什么在if/else语句后不使用分号? [英] Why are semicolons not used after if/else statements?

问题描述

我知道在Javascript中的所有语句后使用分号是一种很好的语法，但是没有人知道为什么在花括号后不需要if/else语句吗?

I understand that it is good syntax to use semicolons after all statements in Javascript, but does any one know why if/else statements do not require them after the curly braces?

推荐答案

• 分号用于结束一个语句
• {和}开始并关闭一组语句
• Semicolon is used to end ONE statement
• { and } begin and close a group of statements

基本上，if-else后面必须带有一个语句或一组语句.

Basically, an if-else must be followed by either a statement or a group of statements.

if-else，后接一条语句:

if (condition) statement;
if (condition); // followed by a statement (an empty statement)

if-else，后跟一组语句:

if (condition) {
   statement;
   statement;
}

if (condition) {
   // followed by a group of statements of zero length
}

如果

if-else后跟一个语句，则必须以;结尾. if-else在以一组语句结尾时不以;结尾，因为;用于结束单个语句，而不是用于结束一组语句.

if-else must end with a ; if it is followed by a single statement. if-else does not end with a ; when followed by a group of statements because ; is used to end a single statement, and is not used for ending a group of statements.

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