Create a file for your Lambda function

To create your Lambda function

1. Create a text file and save it as myDateTimeFunction.js in the SAM-Tutorial directory.

2. Copy the following Node.js code into myDateTimeFunction.js.

   'use strict';
       
       exports.handler = function(event, context, callback) {
       
         if (event.body) {
           event = JSON.parse(event.body);
         }
       
         var sc; // Status code
         var result = ""; // Response payload
       
         switch(event.option) {
           case "date": 
             switch(event.period) {
               case "yesterday":
                 result = setDateResult("yesterday");
                 sc = 200;
                 break;
               case "today":
                 result = setDateResult();
                 sc = 200;
                 break;
               case "tomorrow":
                 result = setDateResult("tomorrow");
                 sc = 200;
                 break;
               default:
                 result = {
                   "error": "Must specify 'yesterday', 'today', or 'tomorrow'."
                 };
                 sc = 400;
                 break;
             }
             break;
             
       /*      Later in this tutorial, you update this function by uncommenting 
               this section. The framework created by Amazon SAM detects the update 
               and triggers a deployment by CodeDeploy. The deployment shifts 
               production traffic to the updated version of this function.
               
               case "time":
               var d = new Date();
               var h = d.getHours();
               var mi = d.getMinutes();
               var s = d.getSeconds();
       
               result = {
                 "hour": h,
                 "minute": mi,
                 "second": s
               };
               sc = 200;
               break;
       */
             default:
               result = {
                 "error": "Must specify 'date' or 'time'."
               };
               sc = 400;
             break;
         }
       
         const response = {
           statusCode: sc,
           headers: { "Content-type": "application/json" },
           body: JSON.stringify( result )
         };
       
         callback(null, response);
       
         function setDateResult(option) {
       
           var d = new Date(); // Today
           var mo; // Month
           var da; // Day
           var y; // Year
       
           switch(option) {
             case "yesterday":
               d.setDate(d.getDate() - 1);
               break;
             case "tomorrow":
               d.setDate(d.getDate() + 1);
             default:
              break;
           }
       
           mo = d.getMonth() + 1; // Months are zero offset (0-11)
           da = d.getDate();
           y = d.getFullYear();
       
           result = {
             "month": mo,
             "day": da,
             "year": y
           };
       
           return result;
         }
       };