回调错误不是 Timeout._onTimeout 处的函数

Question

代码：要回用的命名函数：

console.log('before');

getUser(1, getRepositories);
    // console.log('User',user);

function getRepositories(user) {
    //  console.log(user);
    getRepositories(user.gitHubUsername, getCommits);
}

function getCommits(repos) {
    getCommits(repo, displayCommits);
}

function displayCommits(commits) {
    console.log(commits);
}

console.log('after');

function getUser(id, callback) {
   setTimeout(() => {
    console.log('reading a user from databse...');
    callback({ id: id, gitHubUsername: 'mosh'});
}, 2000);
}

function getRepositories(username, callback) {
    setTimeout(() => { 
    console.log('calling GitHub API...');
    callback(['repo1', 'repo2', 'repo3']);
},2000);
}

function getCommits(repo, callback) {
    setTimeout(() => { 
    console.log('calling GitHub API...');
    callback(['commit']);
},2000);
}

输出：前后从数据库中读取用户... 呼叫 GitHub API... C:\Users\jaini\node\async-demo\index.js:31 回调（['repo1'，'repo2'，'repo3']）； ^

TypeError: callback is not a function
    at Timeout._onTimeout (C:\Users\jaini\node\async-demo\index.js:31:5)
    at listOnTimeout (internal/timers.js:554:17)
    at processTimers (internal/timers.js:497:7)

Answer 1

在index.js的第31行，callback需要作为一个函数来调用（你看它不是橙色的，因为它还没有被声明）

Answer 2

正如您不希望 kids/pets/whatever 具有相同的名称一样，您不应该在同一范围内具有相同名称的 function。那个可怜的 JS 引擎无法决定你想要运行哪个 getRepositories 或 getCommits 函数。尝试重命名这些，您就可以开始了：

console.log('before');

getUser(1, getRepositoriesByUser);

function getRepositoriesByUser(user) {
  getRepositories(user.gitHubUsername, getCommitsByRepo);
}

function getCommitsByRepo(repo) {
  getCommits(repo, displayCommits);
}

function displayCommits(commits) {
  console.log(commits);
}

console.log('after');

function getUser(id, callback) {
  setTimeout(() => {
    console.log('reading a user from database...');
    callback({ id, gitHubUsername: 'mosh' });
  }, 2000);
}

function getRepositories(username, callback) {
  setTimeout(() => {
    console.log('calling GitHub API to get repos...');
    callback(['repo 1', 'repo 2', 'repo 3']);
  }, 2000);
}

function getCommits(repo, callback) {
  setTimeout(() => {
    console.log('calling GitHub API to get commits...');
    callback(['commit A', 'commit B']);
  }, 2000);
}

回调错误不是 Timeout._onTimeout 处的函数

Error of callback is not a function at Timeout._onTimeout

javascript

callback

node.js

node-async