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The JavaScript Interview Handbook: 100+ Interview Questions

Solution Review: Calculate Score

Explore how to solve a calculation challenge by applying JavaScript's filter and reduce methods. Understand filtering array elements by condition and reducing arrays to a single value. This lesson helps you grasp higher-order functions to compute scores effectively.

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Solution

Javascript (babel-node)
function boySum(records){
    const ans = records.filter(({gender}) => gender === 'BOYS')
    var out = ans.reduce((sum, records) => sum +records.value,0)
    return out
}
const records = [
    {
        value: 55,
        gender: "BOYS"
    },
    {
        value: 10,
        gender: "BOYS"
    },
    {
        value: 85,
        gender: "GIRLS"
    },
    {
        value: 12,
        gender: "GIRLS"
    },
    {
        value: 70,
        gender: "BOYS"
    }
]
console.log(boySum(records))

Explanation

To solve this challenge, we make use of two higher-order functions, filter and reduce. Before we discuss the code, let’s understand these functions.

filter: takes a callback function as a parameter and returns a new array containing all the elements from the given array that satisfy the condition set by this function. It also takes an optional ...