DaysToEvent_TextOutput_vanilla.js

DaysToEvent_TextOutput_vanilla.js

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+// In this snippet we are going to calculate 
+// the number of days left until an upcoming month/day 
+// and output the number into a string for a text object.
+
+// Originally sourced from https://www.w3resource.com/javascript-exercises/javascript-basic-exercise-9.php
+// Revised by: Beth Wickerson
+
+// ============================================================
+// Project requirements:
+// Create a 2D or 3D Text Object and name it "daysLeftText".
+
+// Import Spark AR Modules
+const S = require('Scene');
+const T = require('Time');
+const D = require('Diagnostics');
+
+
+(async function () {
+  // Find our text object
+  const [textObject] = await Promise.all([
+    S.root.findFirst('daysLeftText')
+  ]);
+
+  // Create a function to calculate the number of days left
+  function calculateDays(){
+    //
+    // Declaring a Javascript Date:
+    // In JavaScript Date objects are based on a time value 
+    // that is the number of milliseconds since 1 January, 1970 UTC.
+    // While the time value at the heart of a Date object is UTC, the 
+    // basic methods to fetch the date and time or its components all 
+    // work in the local (i.e. host system) time zone and offset.
+
+    // Get today's date according to local time
+    const today = new Date();
+    //
+    // Declare a couple of variables to hold the month and day of our event.
+    // -- JavaScript counts months as a zero-based value between 0 and 11 
+    // -- January is 0, February is 1, and so on
+    // -- Days are counted is an integer between 1 and 31 
+    const eventMonth = 11;
+    const eventDay = 25;
+    // Create a new Date object for our event with the year from today's date 
+    // new Date(year, month, day)
+    var eventDate = new Date(today.getFullYear(), eventMonth, eventDay);
+    // Create a conditional to detect if today is the date of the event, 
+    // If the date matches, add 1 to the year.
+    if (today.getMonth()==eventMonth && today.getDate()>eventDay) {
+      eventDate.setFullYear(eventDate.getFullYear()+1); 
+    }
+    // Declare a variable to hold the number of milleseconds in one day.
+    const one_day = 1000*60*60*24;
+    // 
+    // Calculate the difference between our event date and today's date 
+    // and divide by the number of milliseconds in a day.
+    // We may end up with a difference of one hour if your event crossed
+    // a daylight savings time boundary, but for simplicity we are focusing
+    // only on the number of days.
+    // -- This will result in our number of days left!
+    const days = Math.ceil((eventDate.getTime()-today.getTime())/(one_day));
+    // If your event has passed, you will get a negative number
+    //
+    // Let's create a string to add some text around our number
+    const daysLeft = "Only " + days + " days left until Christmas!";
+    // and check our output in the Console
+    D.log(daysLeft);
+
+    // If you only want to return the number, bypass the daysLeft variable and change line 70 to:
+    // textObject.text = days;
+    textObject.text = daysLeft;
+  }
+  // Envoke our function
+  calculateDays();
+
+})();