How can I check if a file contains a string or a variable in JavaScript?

Question

Is it possible to open a text file with JavaScript (location like http://example.com/directory/file.txt) and check if the file contains a given string/variable?

In PHP this can be accomplished easily with something like:

$file = file_get_contents("filename.ext");
if (!strpos($file, "search string")) {
    echo "String not found!";
} else {
    echo "String found!";
}

Is there a way to do this? I'm running the "function" in a .js file with Node.js, appfog.

Answer 1

You can not open files client side with javascript.

You can do it with node.js though on the server side.

fs.readFile(FILE_LOCATION, function (err, data) {
  if (err) throw err;
  if(data.indexOf('search string') >= 0){
   console.log(data) //Do Things
  }
});

Newer versions of node.js (>= 6.0.0) have the includes function, which searches for a match in a string.

fs.readFile(FILE_LOCATION, function (err, data) {
  if (err) throw err;
  if(data.includes('search string')){
   console.log(data)
  }
});