Angular 2：ngIf指令中的比较运算符==和===有什么区别

Question

我不明白为什么会有这两个运算符。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'=='只检查相等性而'==='检查类型和相等性

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

Angular 2：ngIf指令中的比较运算符==和===有什么区别

Angular 2: what differences between comparison operators == and === in ngIf directive

comparator

operator-keyword

angular