---
id: 587d824b367417b2b2512c47
title: Test if a Variable or Function is Defined
challengeType: 2
videoUrl: ''
localeTitle: 测试变量或函数是否定义
---
## Description
提醒一下,这个项目是基于Glitch的以下入门项目构建的,或者是从GitHub克隆的。使用assert.isDefined()或assert.isUndefined()来使测试通过
## Instructions
## Tests
```yml
tests:
- text: 所有测试都应该通过
testString: 'getUserInput => $.get(getUserInput("url") + "/_api/get-tests?type=unit&n=1").then(data => {assert.equal(data.state,"passed"); }, xhr => { throw new Error(xhr.responseText); })'
- text: 选择正确的断言 - isDefined与isUndefined
testString: 'getUserInput => $.get(getUserInput("url") + "/_api/get-tests?type=unit&n=1").then(data => { assert.equal(data.assertions[0].method, "isDefined", "Null is not undefined"); }, xhr => { throw new Error(xhr.responseText); })'
- text: 选择正确的断言 - isDefined与isUndefined
testString: 'getUserInput => $.get(getUserInput("url") + "/_api/get-tests?type=unit&n=1").then(data => { assert.equal(data.assertions[1].method, "isUndefined", "Undefined is undefined"); }, xhr => { throw new Error(xhr.responseText); })'
- text: 选择正确的断言 - isDefined与isUndefined
testString: 'getUserInput => $.get(getUserInput("url") + "/_api/get-tests?type=unit&n=1").then(data => { assert.equal(data.assertions[2].method, "isDefined", "A string is not undefined"); }, xhr => { throw new Error(xhr.responseText); })'
```
## Challenge Seed
## Solution
```js
// solution required
```