Template code for SAP Spartacus generic-link component

code show as below:

<ng-container *ngIf="isExternalUrl(); else isLocalUrl">
  <a
    [href]="url"
    [attr.target]="target"
    [attr.rel]="rel"
    [attr.id]="id"
    [attr.class]="class"
    [attr.style]="style"
    [attr.title]="title"
  >
    <ng-container *ngTemplateOutlet="content"></ng-container>
  </a>
</ng-container>

This code is a fragment of the Component HTML template in an Angular application. It uses some Angular features such as directives, property binding and template references. I will explain each part of this code one by one.

1. <ng-container *ngIf="isExternalUrl(); else isLocalUrl">

<ng-container>is a special Angular element that is not rendered into the DOM and is only used as a container to wrap other elements and control structures. Here it is used to contain a conditional rendering structure.

*ngIfis a structural directive in Angular for conditionally rendering DOM elements. Here, isExternalUrl()is a method, if the return value is true, then <ng-container>the content inside will be rendered into the DOM. If the return value is false, elsethe template referenced after the statement (here isLocalUrlthe template) will be rendered.

2. <a [href]="url" [attr.target]="target" [attr.rel]="rel" [attr.id]="id" [attr.class]="class" [attr.style]="style" [attr.title]="title">

This is an anchor element ( <a>). It uses attribute binding ( []syntax) to dynamically set the value of HTML attributes. For example, [href]="url"means to urlset the value of the variable to the attribute <a>of the element href. Other properties (such as target, rel, idetc.) are also bound in the same way.

3. <ng-container *ngTemplateOutlet="content"></ng-container>

This is another <ng-container>element, which is used to contain a special directive: *ngTemplateOutlet. This directive allows you to insert an Angular template (eg <ng-template>element) into the DOM. Here, contentit is a template reference, which may be a <ng-template>element or a @ContentChildtemplate content obtained through .

To sum up, this code first judges isExternalUrl()the return value of the method, if it is true, renders an element with dynamic attribute binding <a>, and contentinserts the content of the template into it. If isExternalUrl()returns false, render isLocalUrlthe template (which is not given in this code).

Look at this code again:

<ng-template #content>
  <ng-content></ng-content>
</ng-template>

This code involves two important concepts in Angular: ng-templateand ng-content. Let's explain these two concepts and the meaning of this code separately.

1. ng-templateis an Angular directive for creating reusable template fragments. It is used to wrap a piece of HTML code and store it in a variable using a template reference variable (eg ) so that it can be dynamically inserted or displayed #contentelsewhere via structural directives (eg *ngIfor ). *ngForIt should be noted that ng-templateits contained content is not rendered by default, it will only be rendered when a structural directive inserts it into the DOM tree.

2. ng-contentPart of Angular's Content Projection mechanism. It allows you to insert a component's content into a specified location in the component's template. Simply put, it's a placeholder that tells Angular to replace other content into this location at runtime. ng-contentContent projection makes components more versatile, because you can define some content outside the component, and control the display position of these content inside the component .

Now let's analyze this code:

<ng-template #content>
  <ng-content></ng-content>
</ng-template>

This code creates a contenttemplate reference variable called and uses it within the template ng-content. This means that when this component is used by other components, any content placed between this component's tags will be projected to the ng-contentposition of . And this included ng-contentcan ng-templatebe inserted or displayed elsewhere through structural instructions.

In short, the role of this code is to create a reusable template fragment for projecting the content of the component to the specified location. This makes the component more flexible, because you can define some content outside the component, and control where the content is displayed inside the component.