Author: John Au-Yeung

Sometimes, we want to check a function is async with JavaScript.

In this article, we’ll look at how to check a function is async with JavaScript.

How to check a function is async with JavaScript?

To check a function is async with JavaScript, we can check if the function’s constructor is an instance of the constructor that creates an async function.

For instance, we write

const AsyncFunction = (async () => {}).constructor;

console.log(asyncFn instanceof AsyncFunction)

to get the constructor of the async async () => {} function with the constructor property.

Then we check if asyncFn is an instance of the AsyncFunction constructor with asyncFn instanceof AsyncFunction.

Conclusion

To check a function is async with JavaScript, we can check if the function’s constructor is an instance of the constructor that creates an async function.

Sometimes, we want to fix Nodejs connect cannot find static error.

In this article, we’ll look at how to fix Nodejs connect cannot find static error.

How to fix Nodejs connect cannot find static error?

To fix Nodejs connect cannot find static error, we should install the serve-static package.

We install it by running

npm i serve-static

Then we use it by writing

const connect = require('connect')
const serveStatic = require('serve-static');

const app = connect();

app.use(serveStatic("../public"));
app.listen(5000);

to call app.use with the middleware returned by serveStatic called with the path to the static folder we want to serve.

Conclusion

To fix Nodejs connect cannot find static error, we should install the serve-static package.

Sometimes, we want to return certain fields with .populate() from Mongoose.

In this article, we’ll look at how to return certain fields with .populate() from Mongoose.

How to return certain fields with .populate() from Mongoose?

To return certain fields with .populate() from Mongoose, we can call populate with the fields we want to populate.

For instance, we write

Model
  .findOne({
    _id
  })
  .populate('field', 'name')

to call populate with 'field' and 'name' to populate the field and name fields in the returned documents.

Conclusion

To return certain fields with .populate() from Mongoose, we can call populate with the fields we want to populate.

Sometimes, we want to render a variable as HTML in EJS.

In this article, we’ll look at how to render a variable as HTML in EJS.

How to render a variable as HTML in EJS?

To render a variable as HTML in EJS, we can use various tags.

We write

<% code %>

to run code code which is evaluated but not printed.

We write

<%= code %>

to evaluate and print out code as an escaped string.

And we write

<%- my_form_content %>

to evaluate and print out code as is.

Conclusion

To render a variable as HTML in EJS, we can use various tags.

Sometimes, we want to display Node.js raw Buffer data as Hex string.

In this article, we’ll look at how to display Node.js raw Buffer data as Hex string.

How to display Node.js raw Buffer data as Hex string?

To display Node.js raw Buffer data as Hex string, we can use the buffer toString method.

For instance, we write

buff.toString('hex');

to convert the buff buffer to a string with toString.

We call toString with 'hex' to return a hex version of the raw buffer data.

Conclusion

To display Node.js raw Buffer data as Hex string, we can use the buffer toString method.