检查字符串是否以小写字母开头 [英] Checking if a string starts with a lowercase letter

问题描述

如何使用'if'语句查明字符串是否以小写字母开头？

How would I find out if a string starts with a lowercase letter by using an 'if' statement?

推荐答案

如果你想覆盖的不仅仅是az，你可以使用类似的东西：

If you want to cover more than a-z, you can use something like:

var first = string.charAt(0);
if (first === first.toLowerCase() && first !== first.toUpperCase())
{
  // first character is a lowercase letter
}

两个检查都是必需的，因为有些字符（例如数字）既不是大写也不是小写。例如：

Both checks are needed because there are characters (such as numbers) which are neither uppercase or lowercase. For example:

"1" === "1".toLowerCase() //=> true
"1" === "1".toLowerCase() && "1" !== "1".toUpperCase() //=> true && false => false
"é" === "é".toLowerCase() && "é" !== "é".toUpperCase() //=> true && true => true

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