javascript 检查字符串是否以小写字母开头
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Checking if a string starts with a lowercase letter
提问by TheStandardRGB
How would I find out if a string starts with a lowercase letter by using an 'if' statement?
如何使用“if”语句确定字符串是否以小写字母开头？
回答by Daniel Vandersluis
If you want to cover more than a-z, you can use something like:
如果您想涵盖的不仅仅是 az，您可以使用以下内容：
var first = string.charAt(0);
if (first === first.toLowerCase() && first !== first.toUpperCase())
{
// first character is a lowercase letter
}
Both checks are needed because there are characters (such as numbers) which are neither uppercase or lowercase. For example:
这两项检查都需要，因为存在既不是大写也不是小写的字符（例如数字）。例如：
"1" === "1".toLowerCase() //=> true
"1" === "1".toLowerCase() && "1" !== "1".toUpperCase() //=> true && false => false
"é" === "é".toLowerCase() && "é" !== "é".toUpperCase() //=> true && true => true
回答by kennebec
seems like if a character is not equal to it's upper case state it is lower case.
似乎如果一个字符不等于它的大写状态，它就是小写。
var first = string.charAt(0);
if(first!=first.toUpperCase()){
first character is lower case
}
回答by lincolnk
This seems like an appropriate use of regular expressions.
这似乎是对正则表达式的适当使用。
var match = myString.match(/^[a-z]/);
if (match != null) {
// good match
}
