What is main differences between Angular expression and JavaScript expression?

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Angular expressions are like JavaScript expressions but there is a difference between them as Angular expressions are evaluated against a scope object while JavaScript expressions are evaluated against a global window object.

In an Angular context, the main differences between Angular expressions and JavaScript expressions are as follows:

  1. Context: Angular expressions are evaluated within the context of an AngularJS application, typically within templates or data binding expressions, whereas JavaScript expressions are evaluated within the context of a JavaScript runtime environment, such as a web browser or Node.js.
  2. Data Binding: Angular expressions support two-way data binding, meaning changes in the model automatically reflect in the view and vice versa. JavaScript expressions do not inherently support data binding; you would need to manually handle data updates and view rendering.
  3. Security: Angular expressions are designed with security in mind. They provide protection against certain types of vulnerabilities such as Cross-Site Scripting (XSS) attacks by automatically sanitizing untrusted values. JavaScript expressions do not offer this level of security by default and require manual sanitization.
  4. Feature Set: Angular expressions have a limited feature set compared to JavaScript expressions. They do not support certain JavaScript constructs such as function declarations, operators like new, typeof, etc. This limitation is intentional to keep expressions simple and prevent potentially dangerous operations.
  5. Error Handling: Angular expressions provide better error handling and debugging support compared to plain JavaScript expressions. AngularJS framework typically provides more informative error messages that help developers identify and resolve issues in templates more easily.

In summary, while Angular expressions share some similarities with JavaScript expressions, they are tailored specifically for use within AngularJS applications and offer additional features and security enhancements. Understanding these differences is crucial for effectively developing and maintaining AngularJS applications.