Sometimes, we want to use array reduce with condition in JavaScript.
In this article, we’ll look at how to use array reduce with condition in JavaScript.
How to use array reduce with condition in JavaScript?
To use array reduce with condition in JavaScript, we can call filter before we call reduce.
For instance, write:
const records = [{
value: 24,
gender: "male"
},
{
value: 42,
gender: "female"
},
{
value: 85,
gender: "female"
},
{
value: 12,
gender: "female"
},
{
value: 10,
gender: "male"
}
]
const sumMaleAge = records
.filter(({
gender
}) => gender === 'male')
.reduce((sum, record) => sum + record.value, 0)
console.log(sumMaleAge)
We call records.filter with a callback that returns an array with records entries that have the gender value set to 'male'.
Then we call reduce on the returned array with a callback that returns the sum of the of the value from the filtered records entries.
Therefore, sumMaleAge is 34 since we summed up the value property values from the records entries with gender set to 'male'.
Conclusion
To use array reduce with condition in JavaScript, we can call filter before we call reduce.
