Stuck on an issue?

Lightrun Answers was designed to reduce the constant googling that comes with debugging 3rd party libraries. It collects links to all the places you might be looking at while hunting down a tough bug.

And, if you’re still stuck at the end, we’re happy to hop on a call to see how we can help out.

How to trigger callback method only when it appears on the screen

See original GitHub issue

Screenshot to show issue

screenshot_5

Source code

<template>
  <div>
    <header>
      <nav :class="{sticky:stickyActive}">
        <div class="container">
          <div class="row">
            <img
              v-if="!stickyActive"
              src="../assets/logo-white.png"
              alt="Omnifood Logo"
              class="logo"
            >
            <img v-else src="../assets/logo.png" alt="Omnifood Logo" class="logo-black">
            <ul class="main-nav">
              <li>
                <a href="#">Food Delivery</a>
              </li>
              <li>
                <a href="#">How It Works</a>
              </li>
              <li>
                <a href="#">Our Cities</a>
              </li>
              <li>
                <a href="#">Sign Up</a>
              </li>
            </ul>
          </div>
        </div>
      </nav>

      <div class="hero-text">
        <h1>Goodbye junk food
          <br>Hello super healthy meals
        </h1>
        <a href="#" class="bttn bttn-full">I'm hungry</a>
        <a href="#" class="bttn bttn-ghost">Show me more</a>
      </div>
    </header>

    <section
      class="section-features"
      v-waypoint="{active: true, callback: onWaypoint, options: intersectionOptions}"
    >
      <div class="container">
        <div class="row">
          <h2>get food fast &mdash; not fast food</h2>
          <p
            class="long-copy"
          >Hello, we're Omnifood, your new premium food delivery service. We know you're always busy. No time for cooking. So let us take care of that, we're really good at it, we promise!</p>
        </div>

        <div class="row">
          <div class="col-md-3 box">
            <i class="ion-ios-infinite-outline icon-big"></i>
            <h3>Up to 365 days/year</h3>
            <p>Never cook again! We really mean that. Our subscription plans include up to 365 days/year coverage. You can also choose to order more flexibly if that's your style.</p>
          </div>
          <div class="col-md-3 box">
            <i class="ion-ios-stopwatch-outline icon-big"></i>
            <h3>Ready in 20 minutes</h3>
            <p>You're only twenty minutes away from your delicious and super healthy meals delivered right to your home. We work with the best chefs in each town to ensure that you're 100% happy.</p>
          </div>
          <div class="col-md-3 box">
            <i class="ion-ios-nutrition-outline icon-big"></i>
            <h3>100% organic</h3>
            <p>All our vegetables are fresh, organic and local. Animals are raised without added hormones or antibiotics. Good for your health, the environment, and it also tastes better!</p>
          </div>
          <div class="col-md-3 box">
            <i class="ion-ios-cart-outline icon-big"></i>
            <h3>Order anything</h3>
            <p>We don't limit your creativity, which means you can order whatever you feel like. You can also choose from our menu containing over 100 delicious meals. It's up to you!</p>
          </div>
        </div>
      </div>
    </section>

    <section class="section-meals">
      <ul class="meals-showcase clearfix">
        <li>
          <figure class="meal-photo">
            <img src="../assets/1.jpg" alt="1">
          </figure>
        </li>

        <li>
          <figure class="meal-photo">
            <img src="../assets/2.jpg" alt="2">
          </figure>
        </li>

        <li>
          <figure class="meal-photo">
            <img src="../assets/3.jpg" alt="3">
          </figure>
        </li>

        <li>
          <figure class="meal-photo">
            <img src="../assets/4.jpg" alt="4">
          </figure>
        </li>
      </ul>

      <ul class="meals-showcase clearfix">
        <li>
          <figure class="meal-photo">
            <img src="../assets/5.jpg" alt="5">
          </figure>
        </li>

        <li>
          <figure class="meal-photo">
            <img src="../assets/6.jpg" alt="6">
          </figure>
        </li>

        <li>
          <figure class="meal-photo">
            <img src="../assets/7.jpg" alt="7">
          </figure>
        </li>

        <li>
          <figure class="meal-photo">
            <img src="../assets/8.jpg" alt="8">
          </figure>
        </li>
      </ul>
    </section>
      .......
</template>



<script>
export default {
  data: function() {
    return {
      intersectionOptions: {
        root: null,
        rootMargin: "0px 0px 0px 0px",
        threshold: 0 // [0.25, 0.75] if you want a 25% offset!
      }, // https://developer.mozilla.org/en-US/docs/Web/API/Intersection_Observer_API
      stickyActive: false,
      mobileAppActive: false
    };
  },
  methods: {
    onWaypoint({ going, direction }) {
      if (direction === this.$waypointMap.DIRECTION_TOP) {
        this.stickyActive = true;
      } else if (direction === this.$waypointMap.DIRECTION_BOTTOM) {
        this.stickyActive = false;
      }
    },
    onMobileAppLogo({ going, direction }) {
      if (direction === this.$waypointMap.DIRECTION_TOP)
        this.mobileAppActive = true;
    }
  }
};
</script>