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Solution to Sub-task: Read Files

Explore how to create an asynchronous function in JavaScript that reads all text files within a directory. Understand using promises, filtering file paths, and leveraging Promise.all to handle multiple asynchronous file reads concurrently, returning their contents in a single array.

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Read files

Here, use the directories from earlier as a reference point. Read all files so the path and data of each file is in a single array.

Node.js
// helper function to read a file
// input -> String => Path to file
// Output -> [String, String] => [file path, data of file] 
var readFile = dir => new Promise(ress => fs.readFile(dir,'utf8',(err,data)=>{
	if(err) ress([dir ,'']);
	else ress([dir , data]);
}))
var readFiles = async (dir) => {
	var directories = await getNestedPathNames(dir);
	var txtFiles = directories.filter(x => x.match('.txt'));
	var txtpromises = txtFiles.map(x => readFile(x));
	var arrData = await Promise.all(txtpromises);
	return arrData
}
var test = async () => {
	await populate_directory(); // initialise custom directories in background
	var names = await readFiles('dir'); // get promise and wait for resolve
	console.log(names); // print output of promise
}
test();

In this solution, first make the readFiles function asynchronous by adding the async token to the function (line 9). Then, get all path names in the directory dir utilizing our ...