Touppercase is not a function. Let’s see with help of simple example Description The toUpperCase() method converts a string to uppercase letters. type. It replaces the array with a string, and strings don’t have a join method. Converts all lowercase letters to uppercase. toUpperCase; You’re assigning the toUpperCase function itself to charArray. If you do not want them, start the content on the same line as the opening backtick. 2. Jan 11, 2018 · charArray = charArray[0]. name); } What I Learned JavaScript doesn’t protect you from yourself. To resolve this issue, convert value to string using toString() ,method before calling toUpperCase () method. In this video I'll go through your question, provide various answers & Jul 20, 2025 · } else { console. See the examples below for ideas on typical usage. toUpperCase() ? If you added the () at the end, it will then assign the uppercased char to the charArray variable itself. The resulting string is returned for use in further processing. It helps standardize text for comparison or display. Aug 30, 2020 · Javascript Uncaught TypeError: value. It does not detract from any of the above valid answers: If the object on which the . toUpperCase is not a function occurs when we call toUpperCase() function on object which is not an string. The function receives the string parts and the interpolated values separately: Feb 19, 2026 · Understand the critical difference between TypeScript's 'any' and 'unknown' types. Jun 13, 2019 · Please include the code where you are using name. The toUpperCase() method does not change the original string. My first guess is you didn't call toUpperCase() as a string method, because you left off the parentheses. Maybe you meant charArray[0]. toUpperCase is not a function I'm a newbie to JS so I'm not sure how everything fully works, however I did just add in the GET by the POST because before that I was getting 405 errors. Essential for any sprint review meeting agenda. Learn why 'unknown' is the safer choice, improving code quality and contributing to better metrics on your engineering dashboard. warn("Uppercase not available on this value:", item. toUpperCase() is not a functionThanks for taking the time to learn more. Note that the leading and trailing newlines are included in the string. Tagged Templates Tagged templates are an advanced feature where a function processes the template literal. String. Special characters and digits remain unchanged. ') is NOT updated by the string function. javascript: . The more you assume something exists, the more likely it doesn’t. Basic String Methods Javascript strings are primitive and immutable: All string methods produce a new string without altering the original string. toUpperCase. toUpperCase is not a function" in Javascript Asked 10 years, 5 months ago Modified 10 years, 5 months ago Viewed 7k times Apr 25, 2013 · That's because data method for data-value='1' attribute returns a number and Number object doesn't have toUpperCase method, assuming that your data-* attributes contain both numeric and non-numeric values and you want to convert the non-numeric values to uppercase, you can use attr method instead that returns a string. . For example, when name is "JERRY" then the function should return the string "HELLO, JERRY!" The console logs error: . toUpperCase() method is invoked is not a String, then the runtime doesn't 'find' the method toUpperCase() since that method/function only exists on String objects. The function argument (or just the argument) is declared as a variable, and it's value can change, but this is not important necessarily. Oct 19, 2025 · The <string> part can be any string in double quotes ("), or any function or expression that returns a string. May 25, 2022 · TypeError: . Sep 19, 2015 · Uncaught TypeError: d. Dec 10, 2019 · You have misspelled the uppercase function. Asynchronous Confusion: The undefined That Arrives Too Soon The Jan 16, 2026 · The toUpperCase () method is used to convert all letters in a string to uppercase. Letters that are already uppercase stay the same. The target string (the part before the '. This is called the function argument. toUpperCase is not a function Asked 5 years, 5 months ago Modified 5 years, 5 months ago Viewed 583 times Jul 9, 2015 · "Uncaught TypeError: x. 9 When name is all uppercase, then the function should shout back to the user. The right function for uppercase is toUpperCase() Return value The toUpperCase () function returns the string that is converted to uppercase. Defensive programming is not a luxury — it’s your only armor. toUpperCase () is not a function. toUpperCase() function can be only called on string. toUppercase () In this case, while constructing the function you are already declaring that the function needs a “message” to work with.