Author: John Au-Yeung

To kill child process in Node.js, we call the kill method.

For instance, we write

const proc = require("child_process").spawn("mongod");
proc.kill("SIGINT");

to call spawn to run the mongod program.

Then we call kill with 'SIGINT' to kill the process.

To join tests from multiple files with mocha.js and JavaScript, we use the --recursive option to run all test files in the project.

To do this, we run

$ mocha --recursive

to make mocha find all tests in the project folder and run them.

To turn all the keys of an object to lower case with JavaScript, we use some object methods.

For instance, we write

const newObj = Object.fromEntries(
  Object.entries(obj).map(([k, v]) => [k.toLowerCase(), v])
);

to call Object.entries to return an array of key-valye pair arrays from the obj.

Then we call map with a callback to map the keys to lower case with toLowwerCase and v.

And then we call Object.fromEntries to convert the mapped key-value pair array back to an object.

To ignore incompatible engine "node" error on installing npm dependencies with yarn, we remove the engines entry from the package.json file.

We can also run

yarn config set ignore-engines true

to ignore the engines entry in package.json once by setting the ignore-engines setting to true.

To remove all properties from a object with Node.js, we assign the variable to an empty object.

For instance, we write

req.session = {};

to assign req.session to an empty object to remove all properties from it.