如何使用JavaScript测试字符串中的字母是大写还是小写？ [英] How can I test if a letter in a string is uppercase or lowercase using JavaScript?

问题描述

如何使用JavaScript测试字符串中的字母是大写还是小写？

How can I test if a letter in a string is uppercase or lowercase using JavaScript?

推荐答案

josh的回答如果字符或整个字符串是数字，则maleki将在大写和小写两种情况下返回true。使结果成为错误的结果。
使用josh的例子

The answer by josh and maleki will return true on both upper and lower case if the character or the whole string is numeric. making the result a false result. example using josh

var character = '5';
if (character == character.toUpperCase()) {
 alert ('upper case true');
}
if (character == character.toLowerCase()){
 alert ('lower case true');
}

另一种方法是先测试它是否为数字，否则测试大写或小写
示例

another way is to test it first if it is numeric, else test it if upper or lower case example

var strings = 'this iS a TeSt 523 Now!';
var i=0;
var character='';
while (i <= strings.length){
    character = strings.charAt(i);
    if (!isNaN(character * 1)){
        alert('character is numeric');
    }else{
        if (character == character.toUpperCase()) {
            alert ('upper case true');
        }
        if (character == character.toLowerCase()){
            alert ('lower case true');
        }
    }
    i++;
}

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