_onFocusIn(e) {
        if (this.settings.selectOnFocus) {
            // The whole input content is selected on focus (following the `selectOnFocus` and `selectNumberOnly` options)
            //XXX Firefox <47 does not respect this selection...Oh well.
            this.select();
        } else {
            // Or we decide where to put the caret using the `caretPositionOnFocus` option
            if (!AutoNumericHelper.isNull(this.settings.caretPositionOnFocus)) {
                AutoNumericHelper.setElementSelection(e.target, this._initialCaretPosition(AutoNumericHelper.getElementValue(this.domElement)));
            }
        }
    }
Handler for the 'focusin' event.
This is called before the 'focus' event, and is necessary to change the selection on focus under Firefox for instance.

@param {Event} e
@private