https://github.com/mayosmith/HelloDynamoDB

/*
-----------------------------------------------------------------
AWS configure
Note: this is a simple experiement for demonstration
purposes only. Replace the keys below with your own.
Do not include the secret key in an actual production
environment,because,then,it wont be secret anymore...
-----------------------------------------------------------------
*/
AWS.config.update({accessKeyId: 'AKIAJUPWRIYYQGDB6AFA',secretAccessKey: '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'});
// Configure the region
AWS.config.region = 'us-west-2';  //us-west-2 is Oregon
//create the ddb object
var ddb = new AWS.DynamoDB();
/*
-----------------------------------------------------------------
Update the Table
-----------------------------------------------------------------
*/
//update the table with this data
var params = {
  Key: {
    name: {S: 'John Mayo-Smith'},city: {S: 'New York'}
  },AttributeUpdates: {
    food: {
      Action: 'PUT',Value: {S: 'chocolate'}
    }
  },TableName: 'sampletable',ReturnValues: 'ALL_NEW'
};
//update the table
update();
/*
-----------------------------------------------------------------
Get Item from the Table
-----------------------------------------------------------------
*/
//attribute to read
var readparams = {
 
  Key: {
    name: {S: 'John Mayo-Smith'},AttributesToGet: ['food'],TableName: 'sampletable'
};
//get the item
read();
/*
-----------------------------------------------------------------
function update()
Description: Calls updateItem which is part of the AWS Javascript
SDK.
Returns: JSON object (the object is stringifyed so we can see 
what's going on in the javascript console)
-----------------------------------------------------------------
*/
function update(){
    ddb.updateItem(params,function(err,data) {
        if (err) { return console.log(err); }
        console.log("We updated the table with this: " + JSON.stringify(data));
    });
}
/*
-----------------------------------------------------------------
function read()
Description: Calls getItem which is part of the AWS Javascript
SDK.
Returns: JSON object (the object is stringifyed so we can see 
what's going on in the javascript console)
-----------------------------------------------------------------
*/
function read(){
    ddb.getItem(readparams,data) {
        if (err) { return console.log(err); }
        console.log(": " + data);       
 
    console.log("John's favorite food is: "+ JSON.stringify(data.Item.food.S)); // print the item data
});
}