static getNumericString(domElementOrSelector, callback = null) {
        return this._get(domElementOrSelector, 'getNumericString', callback);
    }
Return the unformatted value as a string from the given DOM element or query selector.
This can also return `null` if `rawValue` is null.

@param {HTMLElement|string} domElementOrSelector
@param {function|null} callback
@returns {string|null}