Inserting dynamic value into array of objects, javascript

Question

I have an array of objects that look something like this;

[
{Number: 5002000, Origin: 123456, Count: 128},
{Number: 5002300, Origin: 900231, Count: 52},
{Number: 5002022, Origin: 534323, Count: 269}
]

Now I'm trying to multiply the "Count" value with a value from a designated price pool.

Which looks something like this;

[
{Prefix: 50023, Price: 20},    
{Prefix: 50020, Price: 10},
{Prefix: 5002, Price: 60},
]

Currently there's an horrendous for loop with if-statements.

for (var key in sData) {
  if (sData[key].Origin.startsWith('50023')) {
    sData[key].sum = (sData[key].Count * 20);
  }
  else if (sData[key].Origin.startsWith('50020')) {
    sData[key].sum = (sData[key].Count * 10);
  }
  // continues...
}

startsWith is a function that simply checks if the value starts with the (value).

Is there already a function in JS to map two arrays of objects? (I'm also having issues with the logic since the "Prefix" value basically has to go from the top down as not to land on the default "5002"-prefix.)

but the prefix 5002 covers the rest of prefixes. What is the priority? — RomanPerekhrest
– RomanPerekhrest, Commented May 16, 2016 at 6:54

Charlie · Accepted Answer · 2016-05-16 06:58:22Z

1

You should use nested loops in this situation. Also switch to Array.forEach method.

sData.forEach(function(item_, key) {

          prices.forEach(function(item) {

             if (sData[key].Origin.startsWith(item.Prefix)) {
                sData[key].sum = (sData[key].Count * item.Price);
             }

          });  

 })

edited May 16, 2016 at 6:58

answered May 16, 2016 at 6:53

Charlie

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4 Comments

HenrikM Over a year ago

Right, that was simple, let me try!

ste2425 Over a year ago

As your manipulating the item in the sData array a map would be preferable over forEach

Charlie Over a year ago

@ste2425 - map method creates a new array. But here the OP needs to modify the original.

ste2425 Over a year ago

@CharlieH I missed that fact my bad, however you could do sData = sData.map(x => {}). Map is meant for manipulating the arrays contents, forEach for iterating. But on the flip side sData = sData.map(x => {}) does look ugly.

dmi3y · Accepted Answer · 2016-05-16 07:14:32Z

1

Assuming that second array can be transformed into the hash:

var tiers = {
    50023: {Prefix: 50023, Price: 20},    
    50020: {Prefix: 50020, Price: 10},
    5002: {Prefix: 5002, Price: 60},
}

You may make it look like this:

for (var key in sData) {
    var key = String(sData[key])
    var keyIndex = key.slice(5)

    if (tiers.hasOwnProperty(keyIndex)) {
        var price = tiers[keyIndex].Price
        sData[key].sum = (sData[key].Count * price)
    } else {
        // Fallback solution
    }
}

Going further you may even think of some recursive solution for fallback.

answered May 16, 2016 at 7:14

dmi3y

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