How to use the keys Method In Javascript
The keys() method returns an array containing all the keys present in the associative array. So, we can use the length property on this array to get the length of the associative array.
Example: Below is the implementation of the above approach
let arr = { "apple": 10, "grapes": 20 };
arr["guava"] = 30;
arr["banana"] = 40;
// Printing the array
// returned by keys() method
console.log(Object.keys(arr))
// printing the size
console.log("Size = " + Object.keys(arr).length)
Output
[ 'apple', 'grapes', 'guava', 'banana' ] Size = 4
Calculate the length of an associative array using JavaScript
In JavaScript, we have normal arrays in which an element is present at a particular index. Whereas Associative arrays are basically Objects in JavaScript where the index is replaced with user-defined keys. Basically, we can say that it stores Key-Value pairs.
Syntax:
let arr = { key1: 'value'1, key2: 'value2', key3: 'value3'}
Here, arr is the associative array, key1, key2, and key3 are its indexes, and value1, value2, and value3 are its elements.
Example: This is a basic example of the associative property.
let arr = {
"apple": 10,
"grapes": 20
};
arr["guava"] = 30;
arr["banana"] = 40;
console.log("Apple = " + arr.apple)
console.log("Banana = " + arr.banana)
Output
Apple = 10 Banana = 40
Length of an associative array: Like in a normal array, an associative array does not have a length property. So we will see other ways to calculate the length of associative arrays.
To calculate the length of an associative array, we will traverse the array element and count all the keys present in the array.
We can calculate the length of an associative array in the following ways:
Table of Content
- Using hasOwnProperty & for…in loop
- Using the keys Method
- Using Object.entries() Method
- Using Object.getOwnPropertyNames() and length property