How to set object properties to null and blank array in JavaScript?

Question

So I have this object for example:

family_background: {
      children: [],
      spouse_surname: null,
      spouse_first_name: null,
      spouse_first_name: null,
      spouse_middle_name: null,
      spouse_occupation: null,
      spouse_employer: null,
      // so forth and so on
}

The way I set the values to null is like this:

  for (var key in family_background) {
    family_background[key] = null;
  }

But I have a property that is equal to an array and by doing the loop, it would set the property to null also instead of a blank array.

How can I fix this? Am I missing something?

So you want to set the property to empty array if it is an array and null otherwise? — Saravana
– Saravana, Commented May 1, 2017 at 2:50
What I don't understand is how did you think that your solution should set it to a blank array. "Am I missing something?" :D please try to use google first — gsanta
– gsanta, Commented May 1, 2017 at 23:04

Mikal Madsen · Accepted Answer · 2017-05-01 02:56:15Z

2

Check if the value is an instanceof Array, and if so, set it to an empty array.

for (var key in family_background) {
    family_background[key] = family_background[key] instanceof Array
        ? []
        : null;
}

answered May 1, 2017 at 2:56

Mikal Madsen

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Comments

Saravana · Accepted Answer · 2017-05-01 03:04:28Z

2

Use Array.isArray to check if your property is an array before you set the values:

for (var key in family_background) {
    family_background[key] = Array.isArray(family_background[key]) ? [] : null;
}

MDN documentation for Array.isArray: https://developer.mozilla.org/en/docs/Web/JavaScript/Reference/Global_Objects/Array/isArray

edited May 1, 2017 at 3:04

answered May 1, 2017 at 2:52

Saravana

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1 Comment

wobsoriano Over a year ago

Thank you for this.

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