Coding⏱️ 2 min read📅 2026-05-31

How to Fix: How to manage Angular2 "expression has changed after it was checked" exception when a component property depends on current datetime

Angular2 expression has changed after it was checked exception when a component property depends on current datetime

Quick Answer: Use the `ngAfterViewInit` lifecycle hook to update the font color based on the current datetime, and use the `ChangeDetectorRef` to detect changes in the component's properties.

The 'expression has changed after it was checked' exception in Angular2 occurs when a component property depends on current datetime. This issue arises because the Angular change detection mechanism is not able to track changes made by user input or external factors, such as date and time changes.

⚠️ Common Causes

  • Changes in the component's input binding, such as changes to a date or time property.

🚀 How to Resolve This Issue

Method 1: Use the ChangeDetectorRef

  1. Step 1: Inject the ChangeDetectorRef into your component.

Method 2: Use the AfterViewChecked lifecycle hook

  1. Step 1: Implement the AfterViewChecked lifecycle hook in your component.

Method 3: Use the ngAfterViewInit lifecycle hook

  1. Step 1: Implement the ngAfterViewInit lifecycle hook in your component.

🎯 Final Words

By applying one of these methods, you can resolve the 'expression has changed after it was checked' exception and ensure that your component's styles are updated correctly based on current datetime.

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