如何在测试中设置或模拟元素scrollHeight和元素clientHeight？

Question

我有一个 javascript 函数来检查 html

通过检查元素 ,el是否具有特定大小：

function isOverflow(element: string): boolean {
    const el = document.getElementById(element);
    return el.scrollHeight > el.clientHeight
}

我想测试一下我的功能。如何设置或模拟scrollHeight和clientHeight？

it('test', () => {
   const el = document.createElement("p")
   el.setAttribute("id", "overflow")

   //How to mock these? This doesn't work "Cannot assign to 'scrollHeight' because it is a read-only property"
   el.clientHeight = 2;
   el.scrollHeight = 1;

   expect(component.isOverflow("overflow")).toBe(true);
  })

Answer 1

弄清楚了：

Object.defineProperty(HTMLElement.prototype, 'scrollHeight', { configurable: true, value: 500 })
Object.defineProperty(HTMLElement.prototype, 'clientHeight', { configurable: true, value: 10 })