javascript - 大括号 {} 内的函数调用

Question

我正在尝试使用主要提供商之一来实现在线聊天。他们建议我嵌入如下代码:

<script type="text/javascript">
  function embedScriptInsideHTMLtags() {
    // responsible code
  }
  {
    embedScriptInsideHTMLtags();
  }
</script>

我的问题是，上面和下面有什么区别:

<script type="text/javascript">
  function embedScriptInsideHTMLtags() {
    // responsible code
  }  
  embedScriptInsideHTMLtags();
</script>

Answer 1

第一个示例使用所谓的 block statement 。在这种情况下，两个示例没有区别。根据 MDN 链接:

Variables declared with var or created by function declarations in non-strict mode do not have block scope. Variables introduced within a block are scoped to the containing function or script, and the effects of setting them persist beyond the block itself. In other words, block statements do not introduce a scope.

但是在严格模式

identifiers declared with let and const do have block scope

和

In strict mode, starting with ES2015, functions inside blocks are scoped to that block. Prior to ES2015, block-level functions were forbidden in strict mode.