将AWS S3存储桶与Web应用程序配合使用

I have created EC2 instances, with a load balancer and auto scaling as described in the documentation for AWS from the following link: http://docs.aws.amazon.com/gettingstarted/latest/wah-linux/getting-started-application-server.html

I would like to store all of the user images and files on a S3 bucket, but I'm not sure of the best way to connect it to my web-app. The web-app has an API coded in PHP, which would need to upload files to the bucket. The front end is coded in JavaScript which would need to be able to access the files. These files will be on every page, and range from user images to documents.

Currently all the media is loaded locally, and nothing is stored on the S3 bucket. The front end and the API are both stored on EC2 instances and would need to access the S3 bucket contents.

What is the most efficient way to load the data stored on the S3 bucket? I have looked into the AWS SDK for JavaScript, but it doesn't seem to be the best way of getting the files. Here is the code that seems relevant:

var s3 = new AWS.S3();
var params = {Bucket: 'myBucket', Key: 'myKey'};
s3.getSignedUrl('getObject', params, function (err, url) {
    console.log("The URL is", url);
});

If this is the way to go, would I have to do this for each image?

Thank you