How to prevent object to add duplicate value and stop excuting function

Question

Hey guys i am adding data to the array as object but i wanted to if there is any duplicate item code so its stop excuting the function and return and if the the condition is true so its take the constructor value and add itno the data structure

This what i try to prevent it from adding the value but its not work as i want

function getNo(b){
for (const [key, value] of Object.entries(data)) {
  let val = value.itemCode;
   if(b === val){
    alert('Its equalt to item code');
     break;}else{ return b;};
}}

----What i want is----- 1) Check if value is duplicate or not from the itemCode constructor 2)If its a duplicate value so its should show and alert and stop excuting the function 3)And add this function into the addItem function to check its duplicate or not 4)I store value in the data array

   var item = function(name,itemCode,stock){
        this.name = name;
        this.itemCode = itemCode;
        this.stock = stock;
    }
    
    var data = [];
    
    function addItem(name,itemCode,stock){
        var Newitem = new item(name,itemCode,stock);
        data.push(Newitem);
    }
    
    addItem('BlueTee',100,50);
    addItem('Yellow tee',101,100);
    addItem('BrownTee',102,120);

Answer 1

There are multiple ways to handle this. Your choice should depend on other use cases.

The easiest way is to define data as a javascript object instead of an array. This would require keys for each object. This would look like this:

var data = {};

function addItem(name, itemCode, stock){
  var newItem = new item(name, itemCode, stock);
  if(data[itemCode] === undefined)
    data[itemCode] = newItem;
}

If you are going to later access data as an array, then you can instead iterate over the array for each insertion. This would look like this:

function addItem(name, itemCode, stock){
  var newItem = new item(name, itemCode, stock);
  if(!data.some(function(x => x.itemCode === itemCode)){
    data.push(newItem);
  }
}

This would be slower than a normal insertion especially for large datasets. If you are going to use a very large dataset and need to be able to access as an array, then I would use a hybrid between the two. The javascript object would be used for direct access to the object. A class-like implementation would be preferred for that, but without using oo, the code would look something like this:

var data = [];
var keys = {};

function addItem(name, itemCode, stock){
  var newItem = new item(name, itemCode, stock);
  if(keys[itemCode] === undefined){
    data.push(newItem);
    keys[itemCode] = data.length - 1;
  }
}

This implementation also gets complicated if you are going to modify the array more than just adding elements