What is the difference between substr and substring in JavaScript?

What is the difference between substr and substring in JavaScript?

For example, what distinguishes the following two statements:

alert(“abc”.substr(0, 2)); and alert(“abc”.substring(0, 2)); They both seem to output “ab.” What are the key differences between javascript substr vs substring?

substr: The first parameter specifies the starting index, and the second parameter specifies the number of characters to extract.

For example: alert("abc".substr(0, 2)); // Outputs: "ab"

substring: The first parameter specifies the starting index and the second parameter specifies the ending index (non-inclusive). If the second parameter is omitted, it extracts till the end of the string.

For example:

alert("abc".substring(0, 2)); // Outputs: "ab"