How to convert string to all lower letters in javascript

It is a short tutorial on how to convert a string to lowercase letters in javascript.

For example, if the input is “Welcome to Cloudhadoop” and Output is “welcome to cloudhadoop”.

There are multiple ways to convert to lower case strings.

Inbuilt in toLowerCase() function in javascript

String provides toLowerCase() function to convert to lowercase letters.



It returns a new string in lowercase letters.

Here is an example

const str = 'Welcome to Cloudhadoop';
const resultStr = str.toLowerCase();
console.log(resultStr); // welcome to cloudhadoop

Convert string in lowercase letters with ASCII code

This example is a custom implementation without using toLowercase

  • Read the string character by characters and iterate using for loop
  • Find each character ASCII code
  • if the character is Upper Case i.e upper letter ASCII code is between 91 and 64.
  • Add 32 to get lowercase ASCII code,
  • Convert ASCII to a character using fromCharCode.
  • append the lower case character to the output string
  • Finally, Return output string

function stringToLowerCase(str) { var output = ‘';

for (var i = 0; i < str.length; i++) { var code = str.charCodeAt(i); if (code > 64 && code < 91) { output += String.fromCharCode(code + 32); } else { output += str.charAt(i); } } return output; }

## Difference between toLowerCase and toLocalLowerCase
`toLowerCase` and `toLocalLowerCase` return a string of lower case letters, But `toLocalLowerCase` takes locale language and convert string differently in lower case.

## Conclusion

Converting string in upper case or normal case to lower case is straightforward.

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