AngularJS $evalAsync

AngularJS $timeout

The $evalAsync in AngularJS is a method used to schedule the execution of a function or expression asynchronously within the current digest cycle. It allows you to queue tasks that are closely related to the current application state, such as model updates or DOM modifications. Importantly, it does not introduce artificial delays, ensuring that code is executed in the right context without disrupting the ongoing digest cycle. This is particularly handy in directives, services, or controllers when we need to defer work that should be integrated smoothly into the application’s current state.

Syntax

Here’s a detailed breakdown of its syntax:

$scope.$evalAsync([expression]);

Parameters

$scope: This is the reference to the AngularJS scope object to which you want to attach the $evalAsync function. The function will execute inside the context of this scope.
expression (optional): An optional function or JavaScript expression to be executed during the next digest cycle. This function typically contains code that modifies the scope or model.

Example: In this example, we use $evalAsync to schedule a function for execution within the next digest cycle. Inside the function, we update the model ($scope.value) to 50. This ensures that the change is properly digested and reflected in the UI.

HTML

<!DOCTYPE html> 
<html> 
  
<head> 
    <title>$evalAsync Example</title> 
    <script src= 
"https://ajax.googleapis.com/ajax/libs/angularjs/1.8.2/angular.min.js"> 
    </script> 
</head> 
  
<body ng-app="evalAsyncApp"
      style="text-align: center"> 
    <div ng-controller="EvalAsyncController"> 
        <h1 style="color: green"> 
            w3wiki 
        </h1> 
        <h2>$evalAsync usage</h2> 
        <p>Value: {{ value }}</p> 
        <button ng-click="updateValue()"> 
              Update Value 
          </button> 
    </div> 
    <script> 
        var evalAsyncApp =  
            angular.module('evalAsyncApp', []); 
  
        evalAsyncApp.controller('EvalAsyncController',  
                                function ($scope) { 
            $scope.value = 42; 
  
            $scope.updateValue = function () { 
                $scope.$evalAsync(function () { 
                    $scope.value = 50; 
                }); 
            }; 
        }); 
    </script> 
</body> 
  
</html>

Outout:

What is the Difference Between $evalAsync and $timeout in AngularJS?

AngularJS is a JavaScript framework, which may be utilized by including it in an HTML web page the usage of a <script> tag. AngularJS enables in extension the HTML attributes with the assistance of directives and binding of data to the HTML with expressions. It provides various tools for handling asynchronous tasks in web applications.

In this article, we will explore the differences between $evalAsync and $timeout in AngularJS and provide examples to illustrate their usage. Two commonly used methods for managing asynchronous operations in AngularJS are $evalAsync and $timeout. While both of these methods allow you to schedule code execution, they serve different purposes and behave differently.

Table of Content

AngularJS $evalAsync
AngularJS $timeout
Difference between $evalAsync and $timeout

Tags:

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