For those who are comfortable with CLI, please have a look at deploylambda.sh
and invokelambda.sh, which can save you a lot of mouse clicks.

Please have the aws CLI tool installed. deploylambda.sh is for
creating/updating lambda functions and invokelambda.sh is for,
invoking lambda functions. They simply call 'aws lambda create',
'aws lambda update', and 'aws lambda invoke' to do the corresponding
actions.

Usage:
Say you have a Test.js to deploy, then calling

./deploylambda.sh Test

will create Test.zip which has Test.js zipped inside and upload it
to create/update the lambda function Test by using your current AWS
credential. Many parameters are hard-coded, like the handler will
be set to Test.handler in this example. Feel free to have a look at
the sources to check how they are set.
After deploying the lambda function, you may want to invoke it to
do some tests. Here you got invokelambda.sh. Say you have a
event_test.json which contains the event object in json format to
feed to the Test function, then calling

./invokelambda.sh Test event_test.json

will invoke it with the event provided, and output the result to
out.txt.