检查字符串中的字母是否为大写

Question

I am trying to complete the Caesar Cipher in JavaScript. I need a peice of code that checks to see if a letter in a string is upper case or lower case.

 const caesar = function(str) { for (i = 0; i < str.length; i++) { if (str[i] === str[i].toUpperCase) { console.log('YES'); } else { console.log('NO'); } } } caesar("HeLLO")

Where am I going wrong?

UPDATE: Additional Question

Here is my full code - I swapped out my check for str[i] = str[i].toUpperCase() TO 64 < asciiNum < 91 but the check doesn't work.

Any idea why using ASCII numbers to check for capital is not working in this instance?

const caesar = function(str, shift) {

  var solved = ""; 

  for (i=0; i < str.length; i++){

   var asciiNum = str[i].charCodeAt();
   console.log(asciiNum);

   if (64 < asciiNum < 91) {      // check for upper cased
   newNum = asciiNum + shift;

        if(newNum > 90){
            solved += String.fromCharCode(newNum - 26);
               } else {
            solved += String.fromCharCode(newNum);
         }

 } else if (96 < asciiNum < 123) {         //check for lower case

   newNum = asciiNum + shift;

        if(newNum > 122){
            solved += String.fromCharCode(newNum - 26);
               } else {
            solved += String.fromCharCode(newNum);   
         }    
      } 

   }

  console.log(solved);

}

caesar("Hello, World!", 5);

Answer 1

Your issue was you weren't calling toUpperCase() . The computer saw it but didn't know it was supposed to run the function. To fix it, just put parentheses.

However, to make it cleaner, I'd restructure this like so:

 // Gets a string from the user to test // Replace this with whatever string should be tested (probably a variable) var str = prompt("What string should be tested?"); const caesar = function(arg) { return arg.split("").every(function(e) { /* Makes an array of characters and tests to see if every character satisfies the conditions */ if (e === e.toUpperCase()) { // If the character is upper case return true; // Return true; the program should test the next character } else { console.log(`${e} was not uppercase`); return false; // Return false // The program should stop, because it detected a lowercase character } }); } console.log(`The result of running caesar() on string '${str}' was ${caesar(str)}`); /* Instead of using console.log inside the function Return the *result* of the function so that you can use it later */

This method is faster to run and a little cleaner.

If you want to check if every letter is uppercase, leave it as it is. If you want to check if some letters are uppercase, change the every to some . If you want to reverse and check if all characters (or some) are lowercase, replace the e === e.toUpperCase() with e === e.toLowerCase() or e.== e.toUpperCase() . If a letter is not uppercase, it puts which one it was in the console and stops checking others. After it's finished, it puts whether all were uppercase in the string.

Answer 2

Only missing part in your code is a paranthesis () in toUpperCase .

Answer 3

You're missing parentheses after toUpperCase .

if (str[i] === str[i].toUpperCase) {

For JS you're trying to access a toUpperCase property instead call a function.