Slice last 2 objects of a column in multidimensional JSON array

Question

I may have overlooked a topic with the same question. But i can't seem to figure it out. I would like to remove the last to items in the column. Tried a forEach but it wouldn't work for me, it deletes the complete first column of myArr (for example). Maby instead of delete a Slice?

For example i have this JSON array (myArr):

    let myArr = JSON.parse(this.responseText);
    let myColumnYears = Object.keys(myArr);
    let myColumnInhabitants = 
    Object.values(myArr[0]);

    myArr.forEach(function() {
          delete myColumnYears[0];
        });

[
 {
    "1996": "7959017",
    "1997": "7968041",
    "1998": "7976789",
    "1999": "7992324",
},
{
    "1996": "10156637",
    "1997": "10181245",
    "1998": "10203008",
    "1999": "10226419",
},
{
    "1996": "7071850",
    "1997": "7088906",
    "1998": "7110001",
    "1999": "7143991",
}
]

And i would like to remove the last 2 objects of each array so the result becomes:

[
{
   "1996": "7959017",
   "1997": "7968041",
},
{
   "1996": "10156637",
   "1997": "10181245",

},
{
   "1996": "7071850",
   "1997": "7088906",
}
]

I'm missing being a little more specific i guess.

Answer 1

You can iterate over array using .map() , pick the properties you are interested in and return them as object.

 let data = [ {"1996": "7959017", "1997": "7968041", "1998": "7976789","1999": "7992324"}, {"1996": "10156637", "1997": "10181245", "1998": "10203008", "1999": "10226419" }, {"1996": "7071850", "1997": "7088906", "1998": "7110001", "1999": "7143991" } ]; let result = data.map(o => ({"1996": o["1996"], "1997": o["1997"]})); console.log(result); 

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Answer 2

What happens if there are more key-pair values in the objects? You will need to modify the map function.

To avoid this, you can use another way to solve this problem. Try adding more key-value pairs in your objects, this code will always delete the last two key-value pairs.

 let data = [ {"1996": "7959017", "1997": "7968041", "1998": "7976789","1999": "7992324"}, {"1996": "10156637", "1997": "10181245", "1998": "10203008", "1999": "10226419" }, {"1996": "7071850", "1997": "7088906", "1998": "7110001", "1999": "7143991" } ]; data.forEach((element, index) => { const keys = Object.keys(element); delete element[keys[keys.length - 1]]; delete element[keys[keys.length - 2]]; }); console.log(data); 

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