fs.access() determines whether a path exists and what permissions a user has to the file or directory at that path.

fs.access doesn't return a result rather, if it doesn't return an error, the path exists and the user has the desired
permissions.

The permission modes are available as a property on the fs object, fs.constants

• fs.constants.F_OK - Has read/write/execute permissions (If no mode is provided, this is the default)
• fs.constants.R_OK - Has read permissions
• fs.constants.W_OK - Has write permissions
• fs.constants.X_OK - Has execute permissions (Works the same as fs.constants.F_OK on Windows)

Asynchronously Check Permissions of a File or Directory

var fs = require('fs');
var path = '/path/to/check';
// checks execute permission
fs.access(path, fs.constants.X_OK, (err) => {
 if (err) {
 console.log("%s doesn't exist", path);
} else {
 console.log('can execute %s', path);
 }
});
// Check if we have read/write permissions
// When specifying multiple permission modes
// each mode is separated by a pipe : `|`
fs.access(path, fs.constants.R_OK | fs.constants.W_OK, (err) => {
 if (err) {
 console.log("%s doesn't exist", path);
 } else {
 console.log('can read/write %s', path);
 }
});

Synchronously Check Permissions of a File or Directory

fs.access also has a synchronous version fs.accessSync. When using fs.accessSync you must enclose it within a try/catch block.

// Check write permission
try {
 fs.accessSync(path, fs.constants.W_OK);
 console.log('can write %s', path);
}
catch (err) {
 console.log("%s doesn't exist", path);
}

With all that being said, I highly recommend you keep learning!

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