Filter values from Arrays in Json (JavaScript)

Question

So I have loaded a JSON object from D3 and now want to filter out some columns from the array. My only problem is that doing:

Object.attribute;

doesn't return what I want. The structure of my JSON object is as follows. It holds 1000 objects and each array hold attributes inside of it. I am getting my data from https://data.raleighnc.gov/resource/xce4-kemu.json, for reference.

If I do

Object[0].attribute;

It returns the actual value of the object, so like "12". Where as I want it to return all the values where that key is present

In the URL you can see an example of the JSON. I want to, for example return a JSON where only the issueddate_mth, statelicnum, and constcompletedofficial attributes are present.

An Snippet of what I tried is:

 var raleigh_data = "https://data.raleighnc.gov/resource/xce4-kemu.json";
d3.json(raleigh_data, function(error, data) {
var filtered_data = data.filter(function(d,i,e) {
return d.issueddate_mth;
});

}

use something like var filteredArray = xxx.filter(callbackFunction) to filter an array (the array in this case is a var called xxx ... you dont want to use a var called Object) ... callbackFunction is a function that accepts 3 arguments, the item, the index and the whole array ... do your logic and return true or false to include/exclude the item in the new array returned — Jaromanda X
– Jaromanda X, Commented Oct 11, 2016 at 2:24
So am I understanding correctly-- you want to iterate over every object in the array and return an array of all values for a given property present in each object? — Alexander Nied
– Alexander Nied, Commented Oct 11, 2016 at 2:25

akosel · Accepted Answer · 2016-10-11 02:49:05Z

3

var data = [your array of 1000 objects]
var filteredData = [];
data.forEach(function(item) { 
    if (item.issueddate_mth && item.statelicnum && item.constcompletedofficial) {
        filteredData.push(item);
    }
});

This will get you an array that only contains items from your original array with the specified properties.

Also, I am not 100% sure if you only want those three properities. If so, you could easily just push { issueddate_mth: item.issueddate_mth, statelicnum: item.statelicnum, constcompletedofficial: item.constcompletedofficial } instead of item in the forEach callback

answered Oct 11, 2016 at 2:49

akosel

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2 Comments

Kalimantan Over a year ago

Is there a way to do the reverse. Meaning that I take out properties that I don't want in the the JSON Object?

Kalimantan Over a year ago

Ok I tried the second part as you specified and it worked like a charm. Thank you!!

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