nodejs reads whether multiple files exist

When developing Node.js, sometimes you need to check whether multiple files exist. In this case, we can use the fs module provided by Node.js to achieve this.

fs module is the file system module of Node.js, which provides methods and functions for operating files. We can use it to read files, write files, rename files, delete files, etc. Below we will demonstrate how to use the fs module to check whether multiple files exist.

First, we need to install Node.js and create a new Node.js project. Go into the project directory and install the fs module using the following command:

npm install fs

Next, we create a file called checkFiles.js. In this file, we will write a function to check if multiple files exist. The code is as follows:

const fs = require('fs');

function checkFiles(files) {
    for(let i = 0; i < files.length; i++) {
        try {
            fs.statSync(files[i]);
        } catch(err) {
            if(err.code === 'ENOENT') {
                console.log("File doesn't exist: ", files[i]);
                return false;
            }
        }
    }
    return true;
}

This function accepts an array of file names as parameters. We then use a for loop to iterate through each file in the array. Inside the loop, we use the fs.statSync() method to check if the file exists. If the file does not exist, this method will throw an ENOENT error, which we can catch and print out that the file does not exist. Finally, a Boolean value is returned indicating whether the file exists.

Now, we can use the following code under the file to call the function and check if multiple files exist:

const files = ['file1.txt', 'file2.txt', 'file3.txt'];
const result = checkFiles(files);
console.log(result);

In this example, we assume three files file1 .txt, file2.txt, file3.txt exist. If all files exist, the function returns true, otherwise it returns false.

If you want to determine whether a single file exists, you can use the following code:

const fs = require('fs');
const filePath = 'file.txt';

try {
    if (fs.existsSync(filePath)) {
        console.log('File exists');
    } else {
        console.log('File does not exist');
    }
} catch(err) {
    console.error(err);
}

This method uses the fs.existsSync() method to check whether the file exists. Returns true if the file exists, false otherwise. Note that when using this method, you need to catch errors through the try...catch statement.

In summary, checking whether multiple files exist can be achieved by looping through the file name array and using the statSync() method in the fs module. To check whether a single file exists, you can use the existsSync() method in the fs module. These methods are very simple and easy to use, and can easily check whether the file exists, which is convenient for us to deal with in Node.js development.

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