diff --git a/libraries/redis-wrapper/index.js b/libraries/redis-wrapper/index.js
index da606655be..8fcb52a978 100644
--- a/libraries/redis-wrapper/index.js
+++ b/libraries/redis-wrapper/index.js
@@ -1,99 +1,150 @@
-_ = require("underscore")
-os = require('os')
-crypto = require('crypto')
+/*
+ * decaffeinate suggestions:
+ * DS101: Remove unnecessary use of Array.from
+ * DS102: Remove unnecessary code created because of implicit returns
+ * DS103: Rewrite code to no longer use __guard__, or convert again using --optional-chaining
+ * DS207: Consider shorter variations of null checks
+ * Full docs: https://github.com/decaffeinate/decaffeinate/blob/master/docs/suggestions.md
+ */
+let RedisSharelatex
+const _ = require('underscore')
+const os = require('os')
+const crypto = require('crypto')
 
-# generate unique values for health check
-HOST = os.hostname()
-PID = process.pid
-RND = crypto.randomBytes(4).toString('hex')
-COUNT = 0
+// generate unique values for health check
+const HOST = os.hostname()
+const PID = process.pid
+const RND = crypto.randomBytes(4).toString('hex')
+let COUNT = 0
 
-module.exports = RedisSharelatex =
-	createClient: (opts = {port: 6379, host: "localhost"})->
-		if !opts.retry_max_delay?
-			opts.retry_max_delay = 5000 # ms
-		
-		if opts.cluster?
-			Redis = require("ioredis")
-			standardOpts = _.clone(opts)
-			delete standardOpts.cluster
-			delete standardOpts.key_schema
-			client = new Redis.Cluster(opts.cluster, standardOpts)
-			client.healthCheck = RedisSharelatex.clusterHealthCheckBuilder(client)
-			RedisSharelatex._monkeyPatchIoredisExec(client)
-		else
-			standardOpts = _.clone(opts)
-			ioredis = require("ioredis")
-			client = new ioredis(standardOpts)
-			RedisSharelatex._monkeyPatchIoredisExec(client)
-			client.healthCheck = RedisSharelatex.singleInstanceHealthCheckBuilder(client)
-		return client
-	
-	HEARTBEAT_TIMEOUT: 2000
-	singleInstanceHealthCheckBuilder: (client) ->
-		healthCheck = (callback) ->
-			RedisSharelatex._checkClient(client, callback)
-		return healthCheck
-	
-	clusterHealthCheckBuilder: (client) ->
-		return RedisSharelatex.singleInstanceHealthCheckBuilder(client)
-	
-	_checkClient: (client, callback) ->
-		callback = _.once(callback)
-		# check the redis connection by storing and retrieving a unique key/value pair
-		uniqueToken = "host=#{HOST}:pid=#{PID}:random=#{RND}:time=#{Date.now()}:count=#{COUNT++}"
-		timer = setTimeout () ->
-			error = new Error("redis client health check timed out #{client?.options?.host}")
-			console.error {
-				err: error,
-				key: client.options?.key # only present for cluster
-				clientOptions: client.options
-				uniqueToken: uniqueToken
-			}, "client timed out"
-			callback(error)
-		, RedisSharelatex.HEARTBEAT_TIMEOUT
-		healthCheckKey = "_redis-wrapper:healthCheckKey:{#{uniqueToken}}"
-		healthCheckValue = "_redis-wrapper:healthCheckValue:{#{uniqueToken}}"
-		# set the unique key/value pair
-		multi = client.multi()
-		multi.set healthCheckKey, healthCheckValue, "EX", 60
-		multi.exec (err, reply) ->
-			if err?
-				clearTimeout timer
-				return callback(err)
-			# check that we can retrieve the unique key/value pair
-			multi = client.multi()
-			multi.get healthCheckKey
-			multi.del healthCheckKey
-			multi.exec (err, reply) ->
-				clearTimeout timer
-				return callback(err) if err?
-				return callback(new Error("bad response from redis health check")) if reply?[0] isnt healthCheckValue or reply?[1] isnt 1
-				return callback()
+module.exports = RedisSharelatex = {
+  createClient(opts) {
+    let client, standardOpts
+    if (opts == null) {
+      opts = { port: 6379, host: 'localhost' }
+    }
+    if (opts.retry_max_delay == null) {
+      opts.retry_max_delay = 5000 // ms
+    }
 
-	_monkeyPatchIoredisExec: (client) ->
-		_multi = client.multi
-		client.multi = (args...) ->
-			multi = _multi.call(client, args...)
-			_exec = multi.exec
-			multi.exec = (callback = () ->) ->
-				_exec.call multi, (error, result) ->
-					# ioredis exec returns an results like:
-					# [ [null, 42], [null, "foo"] ]
-					# where the first entries in each 2-tuple are
-					# presumably errors for each individual command,
-					# and the second entry is the result. We need to transform
-					# this into the same result as the old redis driver:
-					# [ 42, "foo" ]
-					filtered_result = []
-					for entry in result or []
-						if entry[0]?
-							return callback(entry[0])
-						else
-							filtered_result.push entry[1]
-					callback error, filtered_result
-			return multi
-	
-		
-	
+    if (opts.cluster != null) {
+      const Redis = require('ioredis')
+      standardOpts = _.clone(opts)
+      delete standardOpts.cluster
+      delete standardOpts.key_schema
+      client = new Redis.Cluster(opts.cluster, standardOpts)
+      client.healthCheck = RedisSharelatex.clusterHealthCheckBuilder(client)
+      RedisSharelatex._monkeyPatchIoredisExec(client)
+    } else {
+      standardOpts = _.clone(opts)
+      const ioredis = require('ioredis')
+      client = new ioredis(standardOpts)
+      RedisSharelatex._monkeyPatchIoredisExec(client)
+      client.healthCheck = RedisSharelatex.singleInstanceHealthCheckBuilder(
+        client
+      )
+    }
+    return client
+  },
 
+  HEARTBEAT_TIMEOUT: 2000,
+  singleInstanceHealthCheckBuilder(client) {
+    const healthCheck = (callback) =>
+      RedisSharelatex._checkClient(client, callback)
+    return healthCheck
+  },
+
+  clusterHealthCheckBuilder(client) {
+    return RedisSharelatex.singleInstanceHealthCheckBuilder(client)
+  },
+
+  _checkClient(client, callback) {
+    callback = _.once(callback)
+    // check the redis connection by storing and retrieving a unique key/value pair
+    const uniqueToken = `host=${HOST}:pid=${PID}:random=${RND}:time=${Date.now()}:count=${COUNT++}`
+    const timer = setTimeout(function () {
+      const error = new Error(
+        `redis client health check timed out ${__guard__(
+          client != null ? client.options : undefined,
+          (x) => x.host
+        )}`
+      )
+      console.error(
+        {
+          err: error,
+          key: client.options != null ? client.options.key : undefined, // only present for cluster
+          clientOptions: client.options,
+          uniqueToken,
+        },
+        'client timed out'
+      )
+      return callback(error)
+    }, RedisSharelatex.HEARTBEAT_TIMEOUT)
+    const healthCheckKey = `_redis-wrapper:healthCheckKey:{${uniqueToken}}`
+    const healthCheckValue = `_redis-wrapper:healthCheckValue:{${uniqueToken}}`
+    // set the unique key/value pair
+    let multi = client.multi()
+    multi.set(healthCheckKey, healthCheckValue, 'EX', 60)
+    return multi.exec(function (err, reply) {
+      if (err != null) {
+        clearTimeout(timer)
+        return callback(err)
+      }
+      // check that we can retrieve the unique key/value pair
+      multi = client.multi()
+      multi.get(healthCheckKey)
+      multi.del(healthCheckKey)
+      return multi.exec(function (err, reply) {
+        clearTimeout(timer)
+        if (err != null) {
+          return callback(err)
+        }
+        if (
+          (reply != null ? reply[0] : undefined) !== healthCheckValue ||
+          (reply != null ? reply[1] : undefined) !== 1
+        ) {
+          return callback(new Error('bad response from redis health check'))
+        }
+        return callback()
+      })
+    })
+  },
+
+  _monkeyPatchIoredisExec(client) {
+    const _multi = client.multi
+    return (client.multi = function (...args) {
+      const multi = _multi.call(client, ...Array.from(args))
+      const _exec = multi.exec
+      multi.exec = function (callback) {
+        if (callback == null) {
+          callback = function () {}
+        }
+        return _exec.call(multi, function (error, result) {
+          // ioredis exec returns an results like:
+          // [ [null, 42], [null, "foo"] ]
+          // where the first entries in each 2-tuple are
+          // presumably errors for each individual command,
+          // and the second entry is the result. We need to transform
+          // this into the same result as the old redis driver:
+          // [ 42, "foo" ]
+          const filtered_result = []
+          for (const entry of Array.from(result || [])) {
+            if (entry[0] != null) {
+              return callback(entry[0])
+            } else {
+              filtered_result.push(entry[1])
+            }
+          }
+          return callback(error, filtered_result)
+        })
+      }
+      return multi
+    })
+  },
+}
+
+function __guard__(value, transform) {
+  return typeof value !== 'undefined' && value !== null
+    ? transform(value)
+    : undefined
+}