Optimizing Client-Side Date Processing For Sharepoint

The Need for Efficient Date Handling

Date values and operations are used extensively in SharePoint solutions, including formatting dates for display, calculating and comparing dates, and enabling date picker controls for data entry. However, JavaScript date processing can consume excessive client-side resources if not optimized, resulting in poor performance and high latency.

JavaScript dates are surprisingly complex under the hood. Each Date object contains a single numeric value representing milliseconds since January 1st, 1970. Therefore, operations like getting the year or formatting the date for display require non-trivial processing to extract the appropriate Gregorian calendar components. These calculations become very costly when performed repeatedly, such as when rendering date fields in large SharePoint lists.

Excessive date processing directly reduces the responsiveness of SharePoint pages. Complex date logic can monopolize the JavaScript thread, blocking rendering and input response. Moreover, the Date object must reconcile numerous calendar systems and time zones, adding extra overhead. By optimizing date handling, we can dramatically improve list view performance, date picker interactivity, and asynchronous operations.

Table of Contents

Best Practices for Date Formatting

For optimal performance, SharePoint developers should follow several best practices around date formatting and parsing:

Use ISO 8601 (YYYY-MM-DD) dates where possible:
```
let dateString = "2023-12-31";
```

Parse dates just once on initial assignment:

let dateValue = new Date(dateString); // parse once on creation
// ...many references to dateValue...

Use simple, pre-defined formats for display:

dateValue.toLocaleDateString(); // fast built-in format
dateValue.getTime(); // milliseconds since epoch

Avoid excessive dynamic format conversions:

// Anti-pattern - expensive!
let displayDate = new Intl.DateTimeFormat(...).format(dateValue);

By following these rules, we avoid expensive parse and format operations in hot paths. Code should parse string dates once when ingesting data, then leverage simple built-in formats for display. Custom dynamic formats are powerful but complex, and should only be used judiciously.

Caching Date Lookups with JavaScript

Certain date operations like time zone conversions and calendar calculations are complex and expensive. We can eliminate redundant lookups by caching values in JavaScript objects and reusing them.

For example, accessing the browser’s default time zone requires reconciliation between settings, OS, and geolocation. We should cache this value to avoid recalculating per date:

// Cache browser time zone 
let timeZone = Intl.DateTimeFormat().resolvedOptions().timeZone;

// Now we can reuse it
let dateStringEU = new Date().toLocaleString('en-GB', {timeZone});

Similarly, we can cache locale-specific date formats to avoid rebuilding them repeatedly:

// Cache formats
const formats = {
  short: { 
    weekday: 'short',
    year: '2-digit', 
    month: 'short', 
    day: '2-digit' 
  }  
};

// Reuse formats
let dateString = dateValue.toLocaleDateString('en-US', formats.short);

By caching time zones, locales, and formats, we optimize SharePoint date performance by eliminating redundant lookups and regeneration.

Asynchronous Date Processing

JavaScript executes primarily on a single UI thread shared by all page interactivity and rendering. Blocking this thread with long-running date operations can freeze the interface and infuriate users.

We can avoid blocking the main thread by offloading expensive date work to web workers. Web workers enable spawning JavaScript in a separate thread with messaging-based coordination.

For example, we can offload bulk date formatting to a worker:

// Main UI thread
let dates = [date1, date2, ...];
let worker = new Worker('dateWorker.js'); 

// Listen for completed result
worker.onmessage = (formattedDates) => {
  // Render formatted dates 
};

// Send dates to worker   
worker.postMessage(dates);

Inside the web worker script:

// dateWorker.js
onmessage = (dates) => {
  let formattedDates = dates.map(date => {
    return expensiveFormat(date); 
  });
  
  postMessage(formattedDates);  
}

By carefully isolating expensive date operations in web workers, we keep the main UI thread responsive. Users perceive better performance as work occurs in parallel in the background.

Optimizing the Datepicker Control

The SharePoint datepicker allows intuitive date selection, but has several performance caveats:

Avoid reinitializing on every show – cache it instead
Throttle rapid valueChanged events which rebuild the calendar
Use static popout calendars to avoid document reflows
Cache timezone data instead of redundant API calls

Correctly initializing the datepicker is critical:

 
// Suboptimal - don't init every time
$('#datepicker').datepicker({ /* config */ }); 

// Better - init once and reuse
let $picker = $('#datepicker').datepicker({ /* config */ });
$picker.show(); // reuse cached instance

We also must throttle events that trigger expensive calendar rebuilds on every change:

let rebuildCalendar = _.throttle(() => {
  // Rebuild logic
}, 500);

$picker.on('valueChanged', rebuildCalendar);

Follow these guidelines to deliver buttery-smooth datepicker performance.

Testing and Profiling Date Code

Load testing date-heavy workflows is vital to identify performance gaps. Often date bottlenecks only emerge under realistic data volumes and operations.

It’s challenging to debug date performance issues without precise measurements. Using browser profiling tools like the Performance tab, we can quantify the actual duration of date parsing, formatting, and recalculations to pinpoint problems:

In the above example, we catch an anti-pattern – dynamic date formatting in a hot list rendering path. By profiling usage, we validate date optimization opportunities.

Common problematic patterns include:

Unnecessary dynamic date formats
Frequent time zone conversions
Date math operations in list rendering
Excessive Date object creation

Proactively optimizing these areas can significantly boost SharePoint date performance.

Conclusion

Careful optimization of JavaScript date handling unlocks substantial performance gains in SharePoint solutions. Following best practices around date parsing, caching, asynchronous processing, and profiling, we enable smooth user experiences even with date-heavy workloads.

Efficient date code is fast, lightweight, and resilient to data at scale. By considering date performance early in development, we build solutions ready for complex calendar needs and real-world usage.