html获取子节点数量 Selenium-webdriver在JavaScript中获取子元素数

假设我的html是这样的

One

这个js测试文件能够运行,但我试图在选择列表中获取子元素的数量.

var assert = require('assert'),

test = require('selenium-webdriver/testing'),

webdriver = require('selenium-webdriver');

var demoFile = '/path/to/my/test.html';

driver.get(demoFile);

//Setup driver

var driver = new webdriver.Builder().

withCapabilities(webdriver.Capabilities.chrome()).build();

//Get the child elements of select list, which are the options

var ele = driver.findElement(webdriver.By.className('list'))

.findElements(webdriver.By.tagName('option')));

//size is undefined

ele.size();

但是,当我尝试获取选项计数时,我收到以下错误.

TypeError: Object [object Object] has no method 'size'