Add the new value to array of object based on occurrence in javascript

Question

Hi i have an array of objects where i need to include new property or value to object in array based on occurrence

for example: In array of objects there is a property called order number, if object contains the highest orderNumber among the all objects then, add new property called color:red(high risk for understanding), if object contains second highest number among all object leaving the first highest then property called color:green(medium risk) , if third highest number among all objects then property called color:yellow(low risk), also if orderNumber is same then new property value mentioned will be same based on occurrence, and remaining values will have property called color:gray.(no risk)

Here is array :

data = [{
    id: 181,
    name: null,
    orderNumber: 1
  },
  {
    id: 182,
    name: null,
    orderNumber: 1
  },
  {
    id: 183,
    name: null,
    orderNumber: 2
  },
  {
    id: 184,
    name: null,
    orderNumber: 3
  },
  {
    id: 185,
    name: null,
    orderNumber: 3
  },
  {
    id: 186,
    name: null,
    orderNumber: 4
  },
  {
    id: 188,
    name: null,
    orderNumber: 4
  },
  {
    id: 189,
    name: null,
    orderNumber: 4
  },
  {
    id: 190,
    name: null,
    orderNumber: 5
  },
  {
    id: 191,
    name: null,
    orderNumber: 6
  },
]

above in the array need to compare with orderNumber value,

Below is the O/P:

data = [{
    id: 181,
    name: null,
    orderNumber: 1,
    color: gray
  },
  {
    id: 182,
    name: null,
    orderNumber: 1,
    color: gray
  },
  {
    id: 183,
    name: null,
    orderNumber: 2,
    color: gray
  },
  {
    id: 184,
    name: null,
    orderNumber: 3,
    color: gray
  },
  {
    id: 185,
    name: null,
    orderNumber: 3,
    color: gray
  },
  {
    id: 186,
    name: null,
    orderNumber: 4,
    color: yellow
  },
  {
    id: 188,
    name: null,
    orderNumber: 4,
    color: yellow
  },
  {
    id: 189,
    name: null,
    orderNumber: 4,
    color: yellow
  },
  {
    id: 190,
    name: null,
    orderNumber: 5,
    color: green
  },
  {
    id: 191,
    name: null,
    orderNumber: 6,
    color: red
  },
]

In above output color red is for orderNumber: 6 because it is greatest among all, and orderNumber: 5 is color green because it is second highest among all , same for orderNumber: 4 and remaining are gray, just need to assgin three color for first three highest values and remaining color is gray.

It's supposed to be in decreasing order.

StackByMe · Accepted Answer · 2020-08-31 08:15:07Z

You can find the highest order number with Math.max(). Now check the difference from the current order number and apply that color based on an array index.

The solution uses the colors array to add it's colors. If you increase the amount of colors it will show in the output.

const data=[{id:181,name:null,orderNumber:1},{id:182,name:null,orderNumber:1},{id:183,name:null,orderNumber:2},{id:184,name:null,orderNumber:3},{id:185,name:null,orderNumber:3},{id:186,name:null,orderNumber:4},{id:188,name:null,orderNumber:4},{id:189,name:null,orderNumber:4},{id:190,name:null,orderNumber:5},{id:191,name:null,orderNumber:6}];

const applyColor = (arr, colors) => {
  // Get highest number
  const highestNum = arr.reduce((high, item) => item.orderNumber > high ? item.orderNumber : high, 0);
  // Get last color
  const lastColor = colors.pop();
  // Amount of other colors
  const totalColors = colors.length - 1;
  
  // Map a color to each item
  return arr.map(item => {
    // Get the index of the color
    const index = highestNum  - item.orderNumber;
    // If the index is to high, add the last color else add the color at that index
    item.color = index > totalColors ? lastColor : colors[index];
    
    return {...item};
  });
}

// Adding more colors will change the output
const colors1 = ["red", "green", "yellow", "gray"];
const result1 = applyColor(data, colors1);

const colors2 = ["red", "green", "yellow", "orange", "grey"];
const result2 = applyColor(data, colors2);

console.log(result1);
console.log(result2);

No comments:

const data=[{id:181,name:null,orderNumber:1},{id:182,name:null,orderNumber:1},{id:183,name:null,orderNumber:2},{id:184,name:null,orderNumber:3},{id:185,name:null,orderNumber:3},{id:186,name:null,orderNumber:4},{id:188,name:null,orderNumber:4},{id:189,name:null,orderNumber:4},{id:190,name:null,orderNumber:5},{id:191,name:null,orderNumber:6}];

const applyColor = (arr, colors) => {
  const allOrderNums = arr.map(item => item.orderNumber);
  const highestNum = Math.max(...allOrderNums);
  
  const lastColor = colors.pop();
  const totalColors = colors.length - 1;
  
  return arr.map(item => {
    const index = highestNum  - item.orderNumber;
    item.color = index > totalColors ? lastColor : colors[index];
    
    return {...item};
  });
}

const colors1 = ["red", "green", "yellow", "gray"];
const result1 = applyColor(data, colors1);

const colors2 = ["red", "green", "yellow", "orange", "grey"];
const result2 = applyColor(data, colors2);

console.log(result1);
console.log(result2);

thank you so much its working great,just want to know is there any option other then Math.max? and also instead of map cant it be done with reduce method?
@vinuta yes you are right, you can also use reduce instead of map + Math.max. I changed the first snippet with an example that uses reduce.

Collectives™ on Stack Overflow

Add the new value to array of object based on occurrence in javascript

1 Answer 1

2 Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

2 Comments

Your Answer

Sign up or log in

Post as a guest

Related