Question

我不明白为什么这两个运营商存在。在布尔比较的情况下，==和===似乎都有效，但在枚举比较的情况下，只有'=='有效：

<div class="interventionGroup">

    <div class="interventionGroupHeader transition_1s" (click)="onClickHeader()">
        {{GroupName}}
        <div *ngIf="expanded == true" class="expand-icon"><i class="material-icons">expand_less</i></div>  <!-- WORKS -->
        <div *ngIf="expanded === false" class="expand-icon"><i class="material-icons expand-icon">expand_more</i></div> <!-- WORKS -->
    </div>

    <button *ngIf="GroupType == GroupTypeEnum.mesInterventions">dfdsfsd</button> <!-- WORKS -->

    <div style="list-style-type:none" *ngIf="expanded === true">
        <div *ngFor="let intervention of interventions"
            (click)="onClick(intervention)"> 
            <intervention-button [intervention]="intervention"></intervention-button>
        </div>
    </div>
</div>

Answer 1

在javascript中，运算符'=='仅检查相等性，'==='检查类型和相等

0 == '0' => true
0 === '0' => false

Angular 2：ngIf指令中比较运算符==和===之间的差异

1 个答案: