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We can check if a string contains uppercase characters in JavaScript by checking each letter to see if that letter is uppercase in a loop. We will make use of the toUpperCase() and charAt() methods. Here is our function that will check if there are any uppercase letters in a string.
Notice we use a regular expression above to make sure the character is a letter. Here is our function with a simple example:
When processing strings in a program, it can be useful to know if we have uppercase or lowercase characters. Using JavaScript, we can easily check if a string contains uppercase letter(s) with the help of the JavaScript toUpperCase() method. To check if a string contains uppercase, we just need to loop over all letters in the string until we find a letter that is equal to that letter after applying the toUpperCase() method and make sure that character is a letter. Below is our JavaScript function again which will check if a string contains an uppercase letter.
We can also check if a string contains lowercase characters in JavaScript very easily. To check if a string contains lowercase letters in JavaScript, we can adjust our function that we defined above to use the JavaScript toLowerCase() method, instead of the toUpperCase() method. Below is a JavaScript function that will check if a string contains a lowercase letter.
Hopefully this article has been useful for you to learn how to check if a string contains uppercase letters JavaScript. Other Articles You'll Also Like:
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This will return TRUE of FALSE based on whether or not your character matches the character set in the regular expression. Our regular expression checks for all letters a-z So, a basic test would be:
Now we need to determine if it's upper or lower case. So, if we remove the
And just in case it's not a letter, we can add a final else statement:
The above code would work. But it's kinda ugly. Instead, we can use a "ternary operator" to replace our
And these can be nested within each other, too. So a function might look like:
The above code looks good, but won't quite work, because if our character is lower case,
That will work great! But there's no need to have two seperate lines for setting the variable
And we end up with an elegant, concise piece of code. ;) How do you check if all strings are uppercase?To check if a string is in uppercase, we can use the isupper() method. isupper() checks whether every case-based character in a string is in uppercase, and returns a True or False value depending on the outcome.
How do you know if a string is uppercase or lowercase?Traverse the string character by character from start to end. Check the ASCII value of each character for the following conditions: If the ASCII value lies in the range of [65, 90], then it is an uppercase letter. If the ASCII value lies in the range of [97, 122], then it is a lowercase letter.
How do you check if a string is all lowercase Javascript?log(str. toUpperCase() === str. toLowerCase()); If we know that the string is uppercase and it's not equal to it's lowercase variant, then we have an all uppercase string.
How do you check if a string contains any special characters in Javascript?To check if a string contains special characters, call the test() method on a regular expression that matches any special character. The test method will return true if the string contains at least 1 special character and false otherwise.
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