Return isn't executed - Javascript, React.js

Question

I've got a problem with my function, after calling it inside an if statement it works sometimes but it doesn't return the last return it starts again with new value.

Here's data I render:

 listData: [
    [
      {id: 1, title: 'list1'},
      {id: 2, title: 'list2'},
    ],
    {id: 3, title: 'list3'},
  ];

And function:

  isArray(a) {
    return (!!a) && (a.constructor === Array);
  }

  renderList(item, options) {
    if (this.isArray(item) === true) {
      item.map((child, childIndex) => {
        this.renderList(child, options)
      })
    }
    return (
      <List item={item} />
    )
  }

Use Array.isArray, or an actual polyfill, don't roll your own. Also, the recursive call is unnecessary, just return a div with the lists mapped inside it. — Jared Smith
– Jared Smith, Commented Jul 11, 2018 at 11:39
Your item.map() call doesn't have any effect. Even though the children might not be arrays and thus get returned, the result of the map() call is discarded. — user5734311
– user5734311, Commented Jul 11, 2018 at 11:39
@Anna Have you tried the answer below? It works fine. Live code: codesandbox.io/s/6wnn5lxqp3 — user5734311
– user5734311, Commented Jul 11, 2018 at 11:48

Dananjaya Ariyasena · Accepted Answer · 2018-07-11 11:52:00Z

3

renderList(item, options) {
    if ( Array.isArray(item) ) {
      return item.map( (child, childIndex) => {
        return this.renderList(child, options)
      })
    } else {
      return (
         <List item={item} />
      )
    }
}

answered Jul 11, 2018 at 11:52

Dananjaya Ariyasena

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2 Comments

user5734311 Over a year ago

This is basically a duplicate of the answer below. The key point are the missing returns.

Dananjaya Ariyasena Over a year ago

More likely yes, but I used Array.isArray instead of this.isArray

Sergii Vorobei · Accepted Answer · 2018-07-11 11:40:53Z

1

Please try this:

if (this.isArray(item) === true) {
  return item.map((child, childIndex) => {
    return this.renderList(child, options)
  })
}

answered Jul 11, 2018 at 11:40

Sergii Vorobei

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