DOM樹，使用xpath獲取元素 document.evaluate

select_js = """
function getElementByXpath(path) {
  return document.evaluate(path, document, null, XPathResult.FIRST_ORDERED_NODE_TYPE, null).singleNodeValue;
}
ele = getElementByXpath(arguments[0]);
ele.readOnly = false;
ele.value = arguments[1];
"""
driver.execute_script(select_js, "//select[@id='Agency']/following-sibling::div//input",'推薦機構會員20190715')

# 自定義函數getElementByXpath()，通過傳入xpath路徑獲取元素。

function getElementByXpath(path) {
  return document.evaluate(path, document, null, XPathResult.FIRST_ORDERED_NODE_TYPE, null).singleNodeValue;
}