The defaultValue property of the HTMLTextAreaElement interface represents the default text content of this text area. Getting and setting this value is equivalent to getting and setting textContent on the <textarea>.
A string.
In the example below, the defaultValue still returns the value originally written in the HTML. If a default value is set, either via HTML or the defaultValue property, user input will update the value but will not overwrite the defaultValue.
const textareaElement = document.getElementById("comment");
console.log(textArea.defaultValue);
textArea.defaultValue = "This is the default text now!";