StencilJS 检查命名槽是否为空 [英] StencilJS check if named slot is empty

问题描述

我有一个带有两个命名槽的 stencilJS 组件.有没有办法确定插槽是否已分配值?例如，下面的代码片段显示了logo"和菜单"的命名槽.如果两个命名槽都不为空，我如何检查组件内部?理想情况下，我想从组件内部和 componentWillMount() 期间进行检查.谢谢你.

I have a stencilJS component with two named slots. Is there a way to determine if the slots have been assigned values? For instance, the code snippet below show named slots for "logo" and "menu." How can I check inside the component if both named slots are not empty? Ideally I want to check from inside the component and during componentWillMount() . Thank you.

  <koi-menu breakpoint="768" userToggled="false">
      <div class="logo__header " slot="logo"><img src="assets/images/logo.png" /></div>

      <ul class="nav__wrapper list mw8-ns center-m" slot="menu">
        <li class="nav__listitem"><a class="ttu nav__link" href="???">Why Live Grit</a></li>
        <li class="nav__listitem"><a class="ttu nav__link" href="???">Clients</a></li>
        <li class="nav__listitem"><a class="ttu nav__link" href="???">Our Programs</a></li>
        <li class="nav__listitem"><a class="ttu nav__link" href="???">Our Story</a></li>
      </ul>

  </koi-menu>

推荐答案

可以从 componentWillLoad() 函数中的宿主元素检测槽的使用:

The use of a slot can be detected from the host element in the componentWillLoad() function:

hasLogoSlot: boolean;
hasMenuSlot: boolean;

@Element() hostElement: HTMLStencilElement;

componentWillLoad() {
    this.hasLogoSlot = !!this.hostElement.querySelector('[slot="logo"]');
    this.hasMenuSlot = !!this.hostElement.querySelector('[slot="menu"]');
}

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