Struggling to locate the index of the matching object within an array of objects?

Question

Struggling to locate the index of the matching object within an array of objects?

There is a dataset available:

var data = {
  "variants": [{
      "quantity": "20",
      "varientId": 8,
      "currency": "YEN",
      "extraField": {
        "Size": "10",
        "Color": "Red",
        "Material": "Denim"
      },
      "price": "199"
    },
    {
      "quantity": "15",
      "varientId": 10,
      "currency": "YEN",
      "extraField": {
        "Size": "9",
        "Color": "Red",
        "Material": "Denim"
      },
      "price": "249"
    },
    {
      "quantity": "18",
      "varientId": 12,
      "currency": "YEN",
      "extraField": {
        "Size": "8",
        "Color": "Green",
        "Material": "Rubber",
      },
      "price": "279"
    }
  ]
}

In addition to the data, an object is also provided:

var obj = {
        "Size": "10",
        "Color": "Red",
        "Material": "Denim"
      }

An attempt was made to search for the object within the dataset:

var index = null

for(var l = 0; l<data.variants.length; l++){
  if(data.variants[l].extraField === obj){
     index = l  
  } 
}

console.log(index)

Another alternative method using JSON.stringify was also tested:

JSON.stringify(data.variants[l].extraField) === JSON.stringify(obj)

The result obtained from console logging the index variable shows null instead of the expected value of 0, as the obj object matches with the first variant's extrafield.

javascript arrays json object equality-operator

Answer 1

Answer №1

The issue with your current method lies in attempting to directly compare two objects using the === operator, which is not suitable for object comparison. In JavaScript, objects are evaluated based on their reference and not their content. Therefore, even if two objects have identical key-value pairs, they will only be deemed equal if they are indeed the same entity in memory.

To ascertain the index of a matching object in an array, one can utilize the JSON.stringify() function to compare stringified versions of the objects. However, a more efficient solution exists by iteratively comparing individual properties within a loop. Below is a straightforward approach to solving this problem:

var data = {
  // Define your data object here...
};

var obj = {
  // Define your obj object here...
};

var index = null;

for (var i = 0; i < data.variants.length; i++) {
  var currentVariant = data.variants[i];
  var isEqual = true;

  for (var key in obj) {
    if (currentVariant.hasOwnProperty(key) && currentVariant[key] !== obj[key]) {
      isEqual = false;
      break;
    }
  }

  if (isEqual) {
    index = i;
    break;
  }
}

console.log(index);

This code correctly identifies the index of the initial object that matches the properties of the obj object within the data.variants array. It sequentially compares each variant's properties, exiting the loop upon discovering a match and assigning the found index to the index variable.

Answer 2

The issue with your current method lies in attempting to directly compare two objects using the === operator, which is not suitable for object comparison. In JavaScript, objects are evaluated based on their reference and not their content. Therefore, even if two objects have identical key-value pairs, they will only be deemed equal if they are indeed the same entity in memory.

To ascertain the index of a matching object in an array, one can utilize the JSON.stringify() function to compare stringified versions of the objects. However, a more efficient solution exists by iteratively comparing individual properties within a loop. Below is a straightforward approach to solving this problem:

var data = {
  // Define your data object here...
};

var obj = {
  // Define your obj object here...
};

var index = null;

for (var i = 0; i < data.variants.length; i++) {
  var currentVariant = data.variants[i];
  var isEqual = true;

  for (var key in obj) {
    if (currentVariant.hasOwnProperty(key) && currentVariant[key] !== obj[key]) {
      isEqual = false;
      break;
    }
  }

  if (isEqual) {
    index = i;
    break;
  }
}

console.log(index);

This code correctly identifies the index of the initial object that matches the properties of the obj object within the data.variants array. It sequentially compares each variant's properties, exiting the loop upon discovering a match and assigning the found index to the index variable.

Answer 3

Answer №2

When it comes to comparing objects with ===, it won't work because they are different objects and you would be comparing references instead. Instead, a shallow comparison can be used by checking each property. However, the most efficient solution in this scenario is to compare using JSON.stringify, which simplifies the process. Running this code will display the number 0 in the console, indicating the index of the desired object.

var data = {
  "variants": [{
      "quantity": "20",
      "varientId": 8,
      "currency": "YEN",
      "extraField": {
        "Size": "10",
        "Color": "Red",
        "Material": "Denim"
      },
      "price": "199"
    },
    {
      "quantity": "15",
      "varientId": 10,
      "currency": "YEN",
      "extraField": {
        "Size": "9",
        "Color": "Red",
        "Material": "Denim"
      },
      "price": "249"
    },
    {
      "quantity": "18",
      "varientId": 12,
      "currency": "YEN",
      "extraField": {
        "Size": "8",
        "Color": "Green",
        "Material": "Rubber",
      },
      "price": "279"
    }
  ]
}

var obj = {
  "Size": "10",
  "Color": "Red",
  "Material": "Denim"
}

var index = null

for (var l = 0; l < data.variants.length; l++) {
  const isEqual = JSON.stringify(data.variants[l].extraField) === JSON.stringify(obj)
  if (isEqual) {
    index = l
  }
}

console.log(index)

Answer 4

When it comes to comparing objects with ===, it won't work because they are different objects and you would be comparing references instead. Instead, a shallow comparison can be used by checking each property. However, the most efficient solution in this scenario is to compare using JSON.stringify, which simplifies the process. Running this code will display the number 0 in the console, indicating the index of the desired object.

var data = {
  "variants": [{
      "quantity": "20",
      "varientId": 8,
      "currency": "YEN",
      "extraField": {
        "Size": "10",
        "Color": "Red",
        "Material": "Denim"
      },
      "price": "199"
    },
    {
      "quantity": "15",
      "varientId": 10,
      "currency": "YEN",
      "extraField": {
        "Size": "9",
        "Color": "Red",
        "Material": "Denim"
      },
      "price": "249"
    },
    {
      "quantity": "18",
      "varientId": 12,
      "currency": "YEN",
      "extraField": {
        "Size": "8",
        "Color": "Green",
        "Material": "Rubber",
      },
      "price": "279"
    }
  ]
}

var obj = {
  "Size": "10",
  "Color": "Red",
  "Material": "Denim"
}

var index = null

for (var l = 0; l < data.variants.length; l++) {
  const isEqual = JSON.stringify(data.variants[l].extraField) === JSON.stringify(obj)
  if (isEqual) {
    index = l
  }
}

console.log(index)

Struggling to locate the index of the matching object within an array of objects?

Answer №1

Answer №2

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