Using Redis SCAN in NODE

Solution 1:

You can use recursion to keep calling scan until done.

function scanAsync(cursor, pattern, returnSet){

    return redisClient.scanAsync(cursor, "MATCH", pattern, "COUNT", "100").then(
        function (reply) {

            cursor = reply[0];
            var keys = reply[1];
            keys.forEach(function(key,i){
                returnSet.add(key);
            });

            if( cursor === '0' ){
                return Array.from(returnSet);
            }else{
                return scanAsync(cursor, pattern, returnSet)
            }

    });
}

Pass in a Set() to make sure keys aren't duplicated

myResults = new Set();

scanAsync('0', "NOC-*[^listen]*", myResults).map( 
    function( myResults ){ console.log( myResults); }
);

Solution 2:

I realize this is a really old question, but I found all of the other answers very unsatisfying. Here is yet another attempt to scan in a relatively clean way using async await (WITHOUT the use of yet another external dependency). You can easily modify this to continuously delete each set of found keys (you would want to tackle them in batches like this in case there are LOTS). Pushing them into an array just demonstrates one very basic thing you could do with them during this stage.

const redis = require('redis');
const { promisify } = require('util');

const client = redis.createClient({...opts});
const scan = promisify(client.scan).bind(client);

const scanAll = async (pattern) => {
  const found = [];
  let cursor = '0';

  do {
    const reply = await scan(cursor, 'MATCH', pattern);

    cursor = reply[0];
    found.push(...reply[1]);
  } while (cursor !== '0');

  return found;
}

Solution 3:

You can try this snippet to scan (1000) keys per iteration and 'delete`.

var cursor = '0';
function scan(pattern,callback){

  redisClient.scan(cursor, 'MATCH',pattern,'COUNT', '1000', function(err, reply){
    if(err){
        throw err;
    }
    cursor = reply[0];
    if(cursor === '0'){
        return callback();
    }else{

        var keys = reply[1];
        keys.forEach(function(key,i){                   
            redisClient.del(key, function(deleteErr, deleteSuccess){
                console.log(key);
            });
        });


        return scan(pattern,callback);
    }
  });
}

scan(strkey,function(){
    console.log('Scan Complete');
});