What is the rationale behind Angular 2 and Angular 4's use of banana brackets? Is there a particular reason for this departure from AngularJS's pattern?

Although not directly related to coding, the syntax in AngularJS can still be followed:

<input ng-model="hero.name" placeholder="name" type="text">

Here is an example of the syntax used in Angular 2 and its newer versions:

 <input [(ngModel)]="hero.name" placeholder="name" type="text">

Implementing these changes would greatly benefit those transitioning from Angular JS.

Similarly, for ng-repeat, the syntax has changed to ngFor:

<ul ngFor let-item [ngForOf]="items" let-i="index" [ngForTrackBy]="trackByFn">
  <li>...</li>
</ul>

<ul ng-repeat="item in items track by myTrackingFunction(n)">
<li>...</li>
</ul>
javascriptangularangularjstypescript

Answer №1

Utilizing banana brackets enables double way binding functionality.

Discover more about it by checking out:

Binding syntax:

Data binding serves as a mechanism to synchronize user interface with application data values. Rather than manually handling value manipulations in HTML, it is more efficient to delegate this task to a binding framework. By establishing bindings between sources and target HTML elements, the framework takes care of the rest.

Angular offers various forms of data binding, which are extensively covered in this guide following an overview of Angular data binding and its syntax.

Types of binding can be categorized based on the direction of data flow: from the source-to-view, from view-to-source, and bi-directional in the form of two-way binding: view-to-source-to-view.

Answer №2

When it comes to Angular, the use of Banana Brackets—[() ]—is considered a standard method for achieving two-way data-binding. This involves a getter and setter system, where [] represents the setter and () denotes the getter. By combining these elements, developers can facilitate two-way data binding for ngModel.

Using setters [] alone can result in one-way binding.

The newer version of Angular, particularly Angular (2,4+), is essentially a reimagining of the original Angular 1. This rewrite involved incorporating TypeScript as the core language, offering all the latest features of JavaScript along with the advantage of strict typing. This means that programmers can have better control over the type of data being processed within their code.

Despite this overhaul, users are not prevented from using AngularJS, which continues to be developed. Efforts are being made to streamline the process of migrating from AngularJS to the newer versions of Angular.

Answer №3

Imagine a banana enclosed in a box, that is the visual representation of Two-Way Data Binding through a template syntax.

Rather than explicitly stating it like this:

<my-input [text]="val" (textChange)="val=$event"></my-input>

We can simply use the shortened syntax:

<my-input [(text)]="val"></my-input>

But why call it “BANANA IN A BOX”? The quirky name helps us remember the order of brackets used in Two-Way Data Binding.

[] = box
() = banana.
[()] = banana in a box 😃

For more information, check out this article.

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