在循环 * ngFor 中为布尔变量赋值

Question

我的组件 window-container 中有一个 ngFor 循环，其中显示了多个聊天 window (window-item)。我想将一个变量 (changeColor) 设置为 true，其中一个 div 为两个，另一个 div 为 false。我希望能够在两个组件中使用此变量：window-container 和 window-item.

这是我在 window-container.html 中所做的，但它不起作用：

<window-item
  *ngFor="let thread of windows; let i = index"
    [thread]="thread">
      <div *ngIf="i % 2 == 0"> {{this.threadService.changeColor = false}}</div>
      <div *ngIf="i % 2 != 0"> {{this.threadService.changeColor = true}}
    </div>
</window-item>

我希望变量 changeColor 为每个 div 更改值，以便在我的 window-item.html 中写入：

<div [ngClass]="{'window-grey' : !this.threadService.changeColor, 'window-blue': this.threadService.changeColor}">
    <div class="panel-container">
      <div class="panel panel-default">
        ...
      </div>
    </div>
</div>

还有我的 window-item.scss :

.panel-heading {
   .top-bar {
      .window-grey {
         background: grey;
      }
      .window-grey {
         background: grey;
      }
   }
}

Answer 1

你可以这样使用它：

Would suggest you should pass that via odd / even of ngFor

even: boolean: True when the item has an even index in the iterable.

odd: boolean: True when the item has an odd index in the iterable.

<window-item
  *ngFor="let thread of windows; let i = index ; let odd = odd;"
    [thread]="{ thread : thread , changeColor : odd }">
      <!-- <div *ngIf="i % 2 == 0"> {{this.threadService.changeColor = false}} </div>
      <div *ngIf="i % 2 != 0"> {{this.threadService.changeColor = true}} </div> -->
</window-item>

// window-item.html
<div [ngClass]="{'window-grey' : !changeColor, 'window-blue': changeColor}">
    <div class="panel-container">
      <div class="panel panel-default">
        ...
      </div>
    </div>
</div>

WORKING DEMO

在循环 * ngFor 中为布尔变量赋值

Assign a value to a boolean variable in loop * ngFor

html

angular-ng-if

ngfor

angular