How to unbind an array copy in Vue.js

问题:

I am trying to copy one array to another and use this like the new array without any changes to old one:

<div id="app">
    <div class="form-group">
       <label>Test input</label>
       <input v-model="testArray[0].name" type="text" class="form-control" placeholder="Input">
    </div>
    <br>
    <pre>testArray: {{ testArray[0] | json}}</pre>
    <pre>templateArray: {{ templateArray[0] | json  }}</pre>

new Vue({
  el: '#app',
  data: {
      testArray: [],
      templateArray: [{name: "TEST"},], 
  },
  ready: function() {
      this.testArray = this.templateArray.slice(0);
    },
});

the issue is that then I am updating new array 'testArray' I also change old array 'templateArray'.

The script in action: https://jsfiddle.net/4po1cpkp/7/

Is there any way to create new array based on array template without directly binding it to template?

回答1:

As Vue.js documentation says:

Under the hood, Vue.js attaches a hidden property __ob__ and recursively converts the object’s enumerable properties into getters and setters to enable dependency collection. Properties with keys that starts with $ or _ are skipped.

You can store your template array with name started from underscore sign:

  data: {
      testArray: [],
      _templateArray: [{ name: "TEST" }]
  },
  ready: function() {
      this.testArray = this.$data._templateArray;
  }

Or you if need it as a Vue.js object:

this.testArray = JSON.parse(JSON.stringify(this.templateArray));

The second case might be slow for big data.

回答2:

I used Vue extend function Vue.util.extend to copy array with un-binding in Vue 2:

this.items_list.push(Vue.util.extend({}, this.list_item));

回答3:

You can use slice() of array prototype read more in MDN Array.prototype.slice()

this.testArray = [].slice.call(this.templateArray)