Get The Max Id In An Array Of Objects In JavaScript

To get the max id in an array of objects in JavaScript –

  1. Use the map() function to get an array containing just ids of the objects.
  2. Use the Math.max() method to get the max value from this array of ids.
  3. For Internet Explorer, use Math.max.apply() method instead of Math.max() method.
get the max id in an array of objects in javascript

Get The Max Id In An Array Of Objects In JavaScript

To get the max id in an array of objects in JavaScript, you can use the map() function to get an array containing just ids of the objects and then use the Math.max() method to get the max value from this array of ids:

function getMaxId(arr) {

var ids = arr.map(element => {

   return element.id;

});

var max = Math.max(...ids);

console.log(max);

}

getMaxId([{id:1}, {id:2}, {id:3}]); //3

The Math.max() method expects a list of numeric values and returns the maximum value from the list.

In the above code, we use the map() function to get an array of just ids (i.e. element.id) from the given array of objects and then use the spread operator (…) to pass this array of ids as a list of arguments to the Math.max() method.

However, the Math.max() method is not supported in Internet Explorer (IE).

Math.max.apply() To Get The Max Id In An Array Of Objects

If you are using Internet Explorer and getting an error when using the Math.max() method, you can use the Math.max.apply() method instead:

function getMaxId(arr) {

var ids = arr.map(element => {

  return element.id;

});

var max = Math.max.apply(null, ids);

console.log(max);

}

getMaxId([{id:1}, {id:2}, {id:3}]); //3

The Math.max.apply() method is similar to the Math.max() method, except that it takes an array of values as an argument instead of a list of values.

In the above code, we pass null as the first argument to the Math.max.apply() method because the `thisArg` parameter is not used in our code.

The apply() method is used to call a function with a given `thisArg` and an array of arguments. It unpacks the array of arguments and passes them to the function as individual arguments.

reduce() Method To Get The Max Id In An Array Of Objects

You can also use the reduce() method to get the max id in an array of objects:

function getMaxId(arr) {

var max = arr.reduce((prev, curr) => {

  return (prev.id > curr.id) ? prev.id : curr.id

}, -1);

console.log(max);

}

getMaxId([{id:1}, {id:2}, {id:3}]); //3

In the above code, we use the reduce() method to get the object with the max id from the given array of objects.

The reduce() method applies a function to an accumulator and each element in the array (from left to right) to reduce it to a single value.

In our code, we use an arrow function as the first argument to the reduce() method. This function takes two arguments – prev and curr. The prev argument is the previous value returned by the function and curr is the current object being processed.

We compare the id property of prev and curr objects and return the id with the maximum value.

The initialValue parameter of the reduce() method is optional. If omitted, it defaults to the first element in the array. In our code, we have set it to -1.

This is because the reduce() method returns the first element of the array if the initialValue parameter is not provided and the array is empty.

But, in our case, we want to return -1 if the array is empty. That’s why we have set the initialValue parameter to -1.

for Loop To Get The Max Id In An Array Of Objects

You can also use the for loop to get the max id in an array of objects:

function getMaxId(arr) {

var max = 0;

for (let i = 0; i < arr.length; i++) {

  if (arr[i].id > max) {

    max = arr[i].id;

  }

}

console.log(max);

}

getMaxId([{id:1}, {id:2}, {id:3}]); //3

In the above code, we have a variable max initialized with the value 0.

We loop through the array of objects and inside the loop, we compare the id of the current object with the max value.

If the id of the current object is greater than max, we set the max value to the id of the current object.

After the loop completes, we get the maximum id from the array of objects.

forEach() Method To Get The Max Id In An Array Of Objects

You can also use the forEach() method to get the max id in an array of objects:

function getMaxId(arr) {

var max = 0;

arr.forEach(element => {

  if (element.id > max) {

    max = element.id;

  }

});

console.log(max);

}

getMaxId([{id:1}, {id:2}, {id:3}]); //3

In the above code, we have a variable max initialized with the value 0.

We loop through the array of objects using the forEach() method. Inside the forEach() method, we compare the id of the current object with the max value.

If the id of the current object is greater than max, we set the max value to the id of the current object.

After the forEach() method completes, we get the maximum id from the array of objects.

You can also use the sort() method to get the max id in an array of objects:

function getMaxId(arr) {

var max = arr.sort((a, b) => b.id – a.id)[0].id;

  console.log(max);

}

getMaxId([{id:1}, {id:2}, {id:3}]); //3

In the above code, we use the sort() method to sort the array of objects by the id in reverse order.

Then, we get the first element from the sorted array and print the id property.

Conclusion

In this article, you have learned different ways to get the max id in an array of objects in JavaScript.

You can use the reduce() method or any of the looping methods (for loop, forEach()) to get the max id from the given array of objects.

You can also use the sort() method to get the max id in an array of objects.

I hope this article has been helpful to you and that you now know how to get the max id in an array of objects in JavaScript.

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