Locate the position of an item in JavaScript based on its value

My json contains a lengthy list of timezones like the examples below. 

[
 {"value": "Pacific/Niue", "name": "(GMT-11:00) Niue"},
 {"value": "Pacific/Pago_Pago", "name": "(GMT-11:00) Pago Pago"},
 {"value": "Pacific/Honolulu", "name": "(GMT-10:00) Hawaii Time"},
 {"value": "Pacific/Rarotonga", "name": "(GMT-10:00) Rarotonga"},
 {"value": "Pacific/Tahiti", "name": "(GMT-10:00) Tahiti"},
 {"value": "Pacific/Marquesas", "name": "(GMT-09:30) Marquesas"},
 {"value": "America/Anchorage", "name": "(GMT-09:00) Alaska Time"},
 {"value": "Pacific/Gambier", "name": "(GMT-09:00) Gambier"},
 {"value": "America/Los_Angeles", "name": "(GMT-08:00) Pacific Time"},
 {"value": "America/Tijuana", "name": "(GMT-08:00) Pacific Time -  Tijuana"},
 {"value": "America/Vancouver", "name": "(GMT-08:00) Pacific Time - Vancouver"},
]

My system can detect the user's timezone and provides it as a string such as "America/Los_Angeles"

With Javascript, I aim to locate the timezone object for America/Los_Angeles in the json so I can extract its corresponding "name" and populate a form field.

I am aware of the indexOf() method, but I am unsure how to apply it in this context. Is there a straightforward way to handle this or is iterating through the entire list the best approach?

javascriptjson

Answer №1

In my JavaScript code, I am looking to locate the position of America/Los_Angeles within a JSON object so that I can automatically populate a form field with its corresponding "name" value.

To achieve this, you can use the findIndex method:

var index = arr.findIndex(s => s.value == "America/Los_Angeles")

You can then utilize this index to populate the desired field.

Alternatively, you can utilize the find method to directly return an object:

var element = arr.find(s => s.value == "America/Los_Angeles")

Afterwards, you can directly set the name field within the element:

element.name = "somevalue";

Answer №2

To single out specific elements, you can utilize the filter method.

var data = [
    {"value": "Pacific/Niue", "name": "(GMT-11:00) Niue"},
    {"value": "Pacific/Pago_Pago", "name": "(GMT-11:00) Pago Pago"},
    {"value": "Pacific/Honolulu", "name": "(GMT-10:00) Hawaii Time"},
    {"value": "Pacific/Rarotonga", "name": "(GMT-10:00) Rarotonga"},
    {"value": "Pacific/Tahiti", "name": "(GMT-10:00) Tahiti"},
    {"value": "Pacific/Marquesas", "name": "(GMT-09:30) Marquesas"},
    {"value": "America/Anchorage", "name": "(GMT-09:00) Alaska Time"},
    {"value": "Pacific/Gambier", "name": "(GMT-09:00) Gambier"},
    {"value": "America/Los_Angeles", "name": "(GMT-08:00) Pacific Time"},
    {"value": "America/Tijuana", "name": "(GMT-08:00) Pacific Time -  Tijuana"},
    {"value": "America/Vancouver", "name": "(GMT-08:00) Pacific Time - Vancouver"},
]

var searchTerm = "America/Los_Angeles";

var filteredResult = data.filter(obj => obj.value === searchTerm);

console.log(filteredResult);

Documentation: filter

Answer №3

To locate the index of an item within an array, you can utilize the built-in Array.prototype.findIndex() method. For example:

[{x:1},{x:2},{x:3}].findIndex(o => o.x == 2) // => 1

If you are working with an older JavaScript environment that does not support this method, you can create a custom function to achieve the same result. Here is an example function that iterates over the array and returns the index of the first item that matches the specified property:

function findIndexByProperty(array, name, value) {
  for (var i = 0; i < array.length; i++) {
    if (array[i][name] === value) { return i; }
  }
  return -1;
}

Answer №4

Utilize JSON.parse for transforming it into an array. Afterwards, loop through the array to locate the desired field.

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