CODEWITHSUNDEEP
javascriptarrays
mike hennessy
mike hennessy

Reputation: 1679

How to filter out array elements where object may or may not exist?

Consider a JavaScript array like this:

  var testArray=
    [
    {name:'test1', source: {type:'1' },
    {name:'test2',
    {name:'test3', source: {type:'1' }
    {name:'test4',
    {name:'test5', source:{type:'2'},
    {name:'test5', source:{type:'3'},
    ]

I want to filter this array and return all elements except where type===1. However as you can see, some of the elements don't have the source object.

If I do this:

const filteredData = testArray.filter(itm=>itm.source && itm.source.type !=='1')

It removes elements that don't have a source attribute.

How can I filter this array to retrieve all items except for where there is a source.type !== 1 ?

Upvotes: 0

Views: 57

Answers (4)

James
James

Reputation: 387

Change your condition to

!itm.source || itm.source.type !== '1'

This will not filter out any items that don't have the source first. All that remain have source so you are safe to check if it is '1'.

Upvotes: 0

Victor Shinobi Gakiya
Victor Shinobi Gakiya

Reputation: 73

Try this (note that your array is wrong, some of the objects are not closed "}")

 var testArray=[
    {name:'test1', source: {type:'1' }},
    {name:'test2'},
    {name:'test3', source: {type:'1' }},
    {name:'test4'},
    {name:'test5', source:{type:'2'}},
    {name:'test5', source:{type:'3'}},
    ];

const filteredData = testArray.filter(itm=>!itm.source || itm.source.type !=='1')

Upvotes: 0

Unmitigated
Unmitigated

Reputation: 89374

You can use the optional chaining operator. It will cause the expression to evaluate to undefined when trying to access properties on null or undefined.

  var testArray=
    [
    {name:'test1', source: {type:'1' }},
    {name:'test2'},
    {name:'test3', source: {type:'1' }},
    {name:'test4'},
    {name:'test5', source:{type:'2'}},
    {name:'test5', source:{type:'3'}},
    ]
const filteredData = testArray.filter(itm=>itm.source?.type !=='1');
console.log(filteredData);

Upvotes: 1

shadowtime2000
shadowtime2000

Reputation: 128

testArray.filter(i => i.source?.type !== "1")

Will use optional chaining to determine if i.source exists and then checks if it is equal to "1", if it is don't keep it. If not keep it.

Upvotes: 0

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