How can I use jQuery.grep() to dynamically filter an array?

Question

I'm trying to filter an array of objects to remove some elements from it. I'm trying to use jQuery.grep(), but I don't know if that's the best tool for the job.

Every element on my array of objects has a "type" element, and I need to remove the ones with a particular "type" value. But those values are unknown, since they will be provided by the user.

Here's what I'm stuck with:

theNewArray = $.grep(database, function( n ) {
    return ( n.type != /* I don't know what to put here */ );
});

I've tried getting all the "type" values in an array, but I don't know what to do with it.

If you want to change original array (like object) you shouldn't use grep because grep doesn't affect original source. — Hamlet Hakobyan
– Hamlet Hakobyan, Commented Nov 22, 2015 at 8:59
You will have to find out what type values are invalid or what type values are valid, so you can === check or !== check against those values. Maybe share some more context? How is the code being used in your app? — Meldon
– Meldon, Commented Nov 22, 2015 at 9:04
Then the question doesn't make any sense. How do you filter something on an unknown criteria? You don't. — jdlm
– jdlm, Commented Nov 22, 2015 at 9:13

jdlm · Accepted Answer · 2015-11-22 09:06:53Z

2

Use Array.filter to filter out what you don't want, or do want:

var numbers = [1, 2, 3, 4, 5];

// Filter out `3`
var result = numbers.filter(function (number) {
  return number !== 3;
});

alert(result);

answered Nov 22, 2015 at 9:06

jdlm

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1 Comment

Grundy Over a year ago

but seems OP don't know what pass instead 3

Community · Accepted Answer · 2017-05-23 10:27:17Z

1

Ok, in case any other noob came here after me, @Grundy put me on the right path. This is what I ended up using with some context:

//Example of the original array of objects that I want to filter
var database = [
  {
    firstName:"John",
    lastName:"Doe",
    type:"Man"
  },
  {
    firstName:"Jane",
    lastName:"Doe",
    type:"Woman"
  },
];

//Here I put the user input in an array (simplified)
var filterArray = [];
$("#settings a.uncheck").each(function(){
    filterArray.push($(this).data( "type" ));
});

//And here I remove the objects in the original array that have the "type" values in the user input
filteredDatabase = $.grep(database, function( n ) {
  return ( filterArray.indexOf(n.type) == -1 );
});

edited May 23, 2017 at 10:27

CommunityBot

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answered Nov 22, 2015 at 21:06

Unai

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