Measuring the Size of Objects by Key Value

In my JavaScript object, I have an associative array containing different values:

var data = [
{val:1, ref:10, rule:100},
{val:1, ref:12, rule:120},
{val:2, ref:13, rule:165},
];

I am looking to find the length of values based on a specific key (for example, when val == 1). Rather than getting the total length of the entire object, I want to specifically calculate the length of values where val is equal to 1. Despite searching for solutions in various resources, I couldn't find a satisfactory answer and I'm uncertain about its feasibility.

data.filter(item => item.val === 1).length; // Output: 2

Something along those lines...

javascriptarraysassociative-array

Answer №1

If you're looking to .filter out specific elements from an array based on a condition:

var filteredElements = array.filter(function(item) { return item.value === 1 })
filteredElements.length // = 2

The filter method executes a provided function once for each element in the array and creates a new array with all elements that pass the test implemented by the callback function. In this scenario, it returns elements where the value property is equal to 1.

Answer №2

To achieve this, make sure to implement a .filter() method:

array.filter(function(item){return item.value===1}).length

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