如何使用JavaScript测试字符串中的字母是大写还是小写?


当前回答

假设一个字符串只有在至少有一个小写字母的情况下才被认为不全是大写,这可以正常工作。我知道它不像其他人试图做的那样简洁,但它有效吗=)

function isUpperCase(str) {
    for (var i = 0, len = str.length; i < len; i++) {
        var letter = str.charAt(i);
        var keyCode = letter.charCodeAt(i);
        if (keyCode > 96 && keyCode < 123) {
            return false;
        }
    }

    return true;
}

其他回答

更确切地说,是关于被问到的问题。传入一个字符串和一个要检查的位置。和Josh的很接近,只是这个比较的是更大的字符串。会添加作为一个评论,但我还没有这个能力。

function isUpperCase(myString, pos) { 
    return (myString.charAt(pos) == myString.charAt(pos).toUpperCase()); 
}   

function isLowerCase(myString, pos) {
    return (myString.charAt(pos) == myString.charAt(pos).toLowerCase()); 
}

您可以通过使用match方法和regex测试数组是否具有大写或小写字符串,下面只是开始测试的基本基础

  var array = ['a', 'b', 'c', 'A', 'B', 'C', '(', ')', '+', '-', '~', '*'];
  var character = array.join('')
      console.log(character)

  var test = function(search){
      upperCase = search.match(/[A-Z]/g)
      console.log(upperCase)

      lowerCase = search.match(/[a-z]/g)
      console.log(lowerCase)
   }

   test(character)

这个问题显然已经回答过很多次了,但我想分享一下我的解决方案,因为我在给出的答案中没有看到它。

var lower_case = function(letter){
    lowers = "abcdefghijklmnopqrstuvwxyz";
    return letter === letter.toLowerCase() && lowers.indexOf(letter) >= 0
};

var upper_case = function(letter){
    uppers = "ABCDEFGHIJKLMNOPQRSTUVWXYZ";
    return letter === letter.toUpperCase() && uppers.indexOf(letter) >= 0
};

function checkCharType (charToCheck) {
    // body... 
    var returnValue = "O";
    var charCode = charToCheck.charCodeAt(0);

    if(charCode >= "A".charCodeAt(0) && charCode <= "Z".charCodeAt(0)){

        returnValue = "U";

    }else if (charCode >= "a".charCodeAt(0) &&
                charCode <= "z".charCodeAt(0) ){
        returnValue = "L";
    }else if (charCode >= "0".charCodeAt(0) &&
            charCode <= "9".charCodeAt(0)  ) {
        returnValue = "N";
    }
    return returnValue;
}

var myString = prompt("Enter Some text: ", "Hello world !");

switch (checkCharType(myString)) {
    case "U":
        // statements_1
        document.write("First character was upper case");
        break;

    case "L":
        document.write("First character was a lower case");
        break;
    case "N":
        document.write("First character was a number");
        break
    default:
        // statements_def
        document.write("First character was not a character or a number");
        break;
}

Define a Function checkCharType().By declaring the variable returnValue and initialising it to the Character "O" to indicate it's Some other value. U for uppercase; L for Lowercase ; N for number Use the charCodeAt() method to get the character code of the first character. Using if Statement , which check within what range of values the character code falls. If it falls between the character codes for A and Z, Its Uppercase, character code between a and z ,Its Lowercase. and so on. "A".charCode(0) var myChar = new String("A"); myChar.charCodeAt(0); "A" : number code "65“ Check the String

我最近是这样做的:

1)检查字符/字符串s是否是小写的

s. tolowercase () == s && s. touppercase ()

2) s为大写

s. touppercase () == s && s. tolowercase ()

涵盖s包含非字母字符和变音符符号的情况。