How to print a new array from existing array of object javascript

Question

I need to create a new array of objects from the existing array on vuejs.

example first array :

import { ref } from 'vue';

const base_array = ref([
  {id: 1, name: Pill, timing: [morning, noon, evening, night]},
  {id: 2, name: Tablet, timing: [morning, evening]},
])

expected result :

const modified_array = ref([
  {id: 1, name: Pill, timing: [morning]},
  {id: 2, name: Pill, timing: [noon]},
  {id: 3, name: Pill, timing: [evening]},
  {id: 4, name: Pill, timing: [night]},
  {id: 5, name: Tablet, timing: [morning]},
  {id: 6, name: Tablet, timing: [evening]},
])

I've tried forEach and looping the array, but seems can't find the right function. Thank youu

Answer 1

Using flatMap , something like this:

const base_array = ref([
      { id: 1, name: Pill, timing: [morning, noon, evening, night] },
      { id: 2, name: Tablet, timing: [morning, evening] },
    ]);

const modified_array  = ref(base_array.value.flatMap(el => el.timing.map(t => ({id: el.id, name: el.name, timing: [t]}))));

Answer 2

This code should work

const modified_array = ref(
    base_array.value.flatMap(({timing, ...r}) =>
        timing.map(timing => ({...r, timing:[timing]}))
    )
);

However, if you want modified_array to be reactive to changes in base_array - you'd want to use computed not ref for modified_array as in the code snippet below

If you watch, then the modified_array output changes when the base_array changes after three seconds with this code

setTimeout(() => base_array.value[1].timing.push('reactive!!!'), 3000);

Anyway, here's the example of fully functional code for vue3

 const { ref, createApp, computed } = Vue; createApp({ setup() { const base_array = ref([ {id: 1, name: 'Pill', timing: ['morning', 'noon', 'evening', 'night']}, {id: 2, name: 'Tablet', timing: ['morning', 'evening']}, ]); const modified_array = computed(() => base_array.value.flatMap(({ timing, ...r }) => timing.map((t) => ({ ...r, timing: [t] })) ) ); setTimeout(() => base_array.value[1].timing.push('reactive!!!'), 3000); return { base_array, modified_array}; } }).mount('#app');

 .as-console-wrapper { max-height: 0 !important; top: 0; }

 <script src="https://unpkg.com/vue@next"></script> <div id="app"> <ul> <li v-for="({id, name}) in base_array" :key="id"> {{ id }}: {{ name }} </li> </ul> <ul> <li v-for="({id, name, timing}, i) in modified_array" :key="i"> {{ id }}: {{ name }} {{timing[0]}} </li> </ul> </div>

Answer 3

You can simply achieve that by using Array.forEach() along with the Destructuring assignment .

Live Demo :

 const base_array = [ {id: 1, name: 'Pill', timing: ['morning', 'noon', 'evening', 'night']}, {id: 2, name: 'Tablet', timing: ['morning', 'evening']}, ]; let modified_arr = []; let index = 1; base_array.forEach(obj => { const {id, name, timing} = obj; timing.forEach(t => { modified_arr.push({ id: index, name, timing: [t]}) index++; }) }); console.log(modified_arr);