How do i update a particular value in an array in JavaScript

Question

I have the following array

0:{VERSION: 1, CURRENT_DATE: "1900-01-01", CURRENT_ACTIVITY_DATE: "2017-06-22"},
1:{VERSION: 2, PREVIOUS_DATE: "1900-01-01", PREVIOUS_ACTIVITY_DATE: "2017-06-22"}

I need to change the format of the date and update the array with the new formatted date. Any thoughts would be helpful.

the exact problem i am facing is array index is not the same in every row. The code works for "PREVIOUS_ACTIVITY_DATE" but for "CURRENT_ACTIVITY_DATE" the date format remains the same and is not changed. If i have more rows with different index i need to change the format for all rows

I am using moment.js for changing the format and that part is working fine.

Thanks in advance.

I don't even see what your problem could be with the current use case, did you try? — Icepickle
– Icepickle, Commented Nov 6, 2017 at 8:18
hm,, @LS2 I think that you are looking at wrong place for your issue, can you paste longer code, sort of what generates this array or more info.. — Kresimir Pendic
– Kresimir Pendic, Commented Nov 6, 2017 at 8:28

Attila Szász · Accepted Answer · 2017-11-06 08:43:04Z

1

In case if you don't know what are the keys, you can access them by calling var keys = Object.keys(array[0]).

If you want to modify for ex. the current date, then simply you can do it by:

var currentDateKey = keys[1];
array[0][currentDateKey] = "newDateString";

and your array will be modified to the new value.

edited Nov 6, 2017 at 8:43

answered Nov 6, 2017 at 8:35

Attila Szász

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cнŝdk · Accepted Answer · 2017-11-06 08:50:11Z

1

Well simply use Array#map() method over your array, it will update each item dates properties in the array:

arr.map(function(el) {
  if (el["PREVIOUS_ACTIVITY_DATE"])
    el["PREVIOUS_ACTIVITY_DATE"] = new Date(el["PREVIOUS_ACTIVITY_DATE"]);

  if (el["PREVIOUS_DATE"])
    el["PREVIOUS_DATE"] = new Date(el["PREVIOUS_DATE"]);

  if (el["CURRENT_ACTIVITY_DATE"])
    el["CURRENT_ACTIVITY_DATE"] = new Date(el["CURRENT_ACTIVITY_DATE"]);

  if (el["CURRENT_DATE"])
    el["CURRENT_DATE"] = new Date(el["CURRENT_DATE"]);

  return el;
});

Demo:

const arr = [{
    VERSION: 1,
    CURRENT_DATE: "1900-01-01",
    CURRENT_ACTIVITY_DATE: "2017-06-22"
  },
  {
    VERSION: 2,
    PREVIOUS_DATE: "1900-01-01",
    PREVIOUS_ACTIVITY_DATE: "2017-06-22"
  }
];

arr.map(function(el) {
  if (el["PREVIOUS_ACTIVITY_DATE"])
    el["PREVIOUS_ACTIVITY_DATE"] = new Date(el["PREVIOUS_ACTIVITY_DATE"]);

  if (el["PREVIOUS_DATE"])
    el["PREVIOUS_DATE"] = new Date(el["PREVIOUS_DATE"]);

  if (el["CURRENT_ACTIVITY_DATE"])
    el["CURRENT_ACTIVITY_DATE"] = new Date(el["CURRENT_ACTIVITY_DATE"]);

  if (el["CURRENT_DATE"])
    el["CURRENT_DATE"] = new Date(el["CURRENT_DATE"]);

  return el;
});

console.log(arr);

Note:

You need to check over the existence of the keys in the object.
I used new Date(el["PREVIOUS_ACTIVITY_DATE"]) as an example here, you just need to change it with your momentjs syantax.

edited Nov 6, 2017 at 8:50

answered Nov 6, 2017 at 8:21

cнŝdk

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3 Comments

LS2 Over a year ago

Thanks for the reply. I guess i have not explained the question correctly. But the exact problem i am facing is array index is not the same in every row. The code works for "PREVIOUS_ACTIVITY_DATE" but for "CURRENT_ACTIVITY_DATE" the date format remains the same and is not changed. If i have more rows with different index i need to change the format for all rows.

cнŝdk Over a year ago

@LS2 Please update your question with your code, anyway using Array.map() will work with all items even if they have the same index like you said.

cнŝdk Over a year ago

@LS2 I think I understand what you mean, you need to check the existence of the keys in the object, before trying to change them. Please check my Edit.

FyZ1K · Accepted Answer · 2017-11-06 08:28:40Z

0

You could go for some approach like:

var myArray = [
    {VERSION: 1, CURRENT_DATE: "1900-01-01", CURRENT_ACTIVITY_DATE: "2017-06-22"},
    {VERSION: 2, PREVIOUS_DATE: "1900-01-01", PREVIOUS_ACTIVITY_DATE: "2017-06-22"}
];

//Format all entries with the desired keys...
var formatKeys = ["CURRENT_DATE","CURRENT_ACTIVITY_DATE","PREVIOUS_DATE","PREVIOUS_ACTIVITY_DATE"];

// Iterate through your array
for(var i = 0; i < myArray.length; i++){
    // Iterate through the desired keys to format
    for(var key in formatKeys){
         if(myArray[i][formatKeys[key]] !== undefined)
         myArray[i][formatKeys[key]].format(); // Your format call
    }
}

answered Nov 6, 2017 at 8:28

FyZ1K

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