The minLength property of the HTMLInputElement interface indicates the minimum number of characters (in UTF-16 code units) required for the value of the <input> element to be valid. It reflects the element's minlength attribute. -1 means there is no minimum length requirement.
Note: If the input has a value, and that value has fewer characters than the minlength attribute requires, the element is considered invalid and the ValidityState object's tooShort property will be true.
A number representing the element's minlength if present or -1.
Given the following HTML:
<p>
<label for="password">Your password</label>
<input id="password" type="password" minlength="8" maxlength="20" />
</p>You can use the minLength property to retrieve or set the <input>'s minlength attribute value:
const inputElement = document.querySelector("#password");
console.log(`Element's minLength: ${inputElement.minLength}`); // "Element's minlength: 8"
inputElement.minLength = 12; // updates the element's minlength attribute value