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Element is undefined because it is not rendered yet. How to wait for it?


In my Vue app I have an image element with a bound src. this code is in a stepper. In one step the user selects a picture to upload an in the next step the image gets shown (which works as intended). However I am trying to initiate a library on the element in the next step (the Taggd library) but the element seems to be undefined.

I tried the nextTick() to wait for the image to load but without luck.

the image element:

<div class="orientation-landscape">
    <div class="justify-center q-px-lg">
        <img v-if="photo.url" :src="photo.url" id="workingPhoto"
        style="width: 80vw;" ref="workingPhoto"/>
    </div>
</div>

The functions. I first use uploadFile to set the url of the image element and go to the next step where the image will be loaded. then I call initTaggd() on the nextTick however that fails because the element is undefined.

uploadFile(file) {
  const self = this;
  self.photo.file = file;
  self.setPhotoUrl(file);
  self.$refs.stepper2.next();
  console.log('We should be at next step now. doing the init');
  self.nextTick(self.initTaggd());
},

setPhotoUrl(file) {
  const self = this;
  self.photo.url = URL.createObjectURL(file);
  console.log('ping1');
},

initTaggd() {
  const self = this;
  const image = document.getElementById('workingPhoto');
  console.log('image:', image);     //THIS RETURNS UNDEFINED
  console.log('Trying ANOTHER element by refs:', self.$refs.stepper2);     // This returns the element
  console.log('trying the real element by reference', self.$refs.workingPhoto);     // Returns undefined again
  const taggd = new Taggd(image);      //All this here fails because image is undefined.
  console.log('ping2.5');
  taggd.setTags([
    self.createTag(),
    self.createTag(),
    self.createTag(),
  ]);
  console.log('ping3');
},

I think I am looking for a way to wait for the image to fully load before calling initTaggd() but I am lost on how to achieve this.


Solution

  • You could listen for the load event:

    <img 
        v-if="photo.url" 
        id="workingPhoto"
        ref="workingPhoto"
        :src="photo.url"
        style="width: 80vw;" 
        @load="initTaggd"
    />