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)   } }); 

Answer 2

You can also use a stream. They can handle larger files. For example:

var fs = require('fs'); var stream = fs.createReadStream(path); var found = false;  stream.on('data',function(d){   if(!found) found=!!(''+d).match(content) });  stream.on('error',function(err){     then(err, found); });  stream.on('close',function(err){     then(err, found); }); 

Either an 'error' or 'close' will occur. Then, the stream will close since the default value of autoClose is true.