express - "Cannot read property 'length' of undefined" when iterating array

Question

I am trying to iterate through an array of objects using express.

This is the iteration in Pug.

each thing in things
    div.Test
        div= thing.name
        div= thing.id

And this is how the Express route looks like.

app.get("/", async (req, res) => {
  const things = [
    {
      name: "Foo bar",
      id: 1,
    },
    {
      name: "Another foo bar",
      id: 2,
    },
    {
      name: "Here we go again",
      id: 7888822,
    },
  ];

  res.render("index", {
    things: things,
  });
});

While the iteration works, I can see that the console spits out these error messages.

Cannot read property 'length' of undefined
    at eval (eval at wrap (/this/is/not/the/real/path/node_modules/pug-runtime/wrap.js:6:10), <anonymous>:97:32)
    at eval (eval at wrap (/this/is/not/the/real/path/node_modules/pug-runtime/wrap.js:6:10), <anonymous>:128:4)
    at template (eval at wrap (/this/is/not/the/real/path/node_modules/pug-runtime/wrap.js:6:10), <anonymous>:131:7)
    at Object.exports.renderFile (/this/is/not/the/real/path/node_modules/pug/lib/index.js:452:38)
    at Object.exports.renderFile (/this/is/not/the/real/path/node_modules/pug/lib/index.js:442:21)
    at View.exports.__express [as engine] (/this/is/not/the/real/path/node_modules/pug/lib/index.js:491:11)
    at View.render (/this/is/not/the/real/path/node_modules/express/lib/view.js:135:8)
    at tryRender (/this/is/not/the/real/path/node_modules/express/lib/application.js:640:10)
    at Function.render (/this/is/not/the/real/path/node_modules/express/lib/application.js:592:3)
    at ServerResponse.render (/this/is/not/the/real/path/node_modules/express/lib/response.js:1012:7)

Answer 1

等待大神答复