Locate the position of an item in an array based on a certain value assigned to a particular

I am trying to locate the index number of a specific item within my object. Here is the object in question:

[
  {
    "type": "Grayscale",
    "mode": "average"
  }, {
    "type": "Sepia"
  }, {
    "type": "Invert",
    "invert": true
  }, {
    "type": "Convolute",
    "opaque": false,
    "matrix": [1, 1, 1, 1, 0.7, -1, -1, -1, -1]
  }, {
    "type": "Convolute",
    "opaque": false,
    "matrix": [0, -1, 0, -1, 5, -1, 0, -1, 0]
  }, {
    "type": "Brownie"
  }, {
    "type": "Brightness",
    "brightness": 0.35
  }
]

My goal is to find the index number of the item that has a value of Invert for the type property. In this case, the desired output would be 2. The search should only consider the values of the type key.

javascriptarraysjavascript-objects

Answer №1

To locate the index of a specific element in an array, utilize the `findIndex` method alongside a custom defined callback function.

let arr = [ {"type":"Grayscale","mode":"average"}, {"type":"Sepia"}, {"type":"Invert","invert":true}, {"type":"Convolute","opaque":false,"matrix":[1,1,1,1,0.7,-1,-1,-1,-1]}, {"type":"Convolute","opaque":false,"matrix":[0,-1,0,-1,5,-1,0,-1,0]}, {"type":"Brownie"}, {"type":"Brightness","brightness":0.35} ], key = 'type';
console.log(arr.findIndex(elem => elem[key] == 'Invert'));

Answer №2

Check out this brief code snippet.

var example = [{"type":"Grayscale","mode":"average"},{"type":"Sepia"},{"type":"Invert","invert":true},{"type":"Convolute","opaque":false,"matrix":[1,1,1,1,0.7,-1,-1,-1,-1]},{"type":"Convolute","opaque":false,"matrix":[0,-1,0,-1,5,-1,0,-1,0]},{"type":"Brownie"},{"type":"Brightness","brightness":0.35}]  

function findIndex(data, keyfield, value){
  
  return data.indexOf(data.find(function(el,index){
    return el[keyfield] === value;
  }));
}

console.log(findIndex(example, 'type', 'Invert'));

Answer №3

If you're looking to enhance your array operations, consider utilizing either the underscore or loadash(_) package. These packages offer a range of functionalities to streamline your array manipulation tasks.

const _ = require('lodash')

let sampleArray=  [
      {"name":"John Doe","age":30},
      {"name":"Jane Smith","age":25},
      {"name":"Michael Johnson","age":35}
    ];
    
let index = _.findIndex(sampleArray, element=> element.name === "Jane Smith");
alert(index);

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