Splitting arrays by a condition
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Posted on We can split arrays in two based on a condition. Everything that matches the condition goes into the first result, everything that doesn’t goes into the second result.
// an array we want to split into two arrays based on a condition
const names = ["Michael", "Jim", "Dwight", "Pam", "Ryan"]
// accepts array and function returning `true` or `false` for each element
const partition = (array, callback) => {
const matches = []
const nonMatches = []
// push each element into array depending on return value of `callback`
array.forEach(element => (callback(element) ? matches : nonMatches).push(element))
return [matches, nonMatches]
}
// destructure matches as `shortNames` and non-matches as `longNames`
const [shortNames, longNames] = partition(names, name => name.length <= 3)
// ⇒ shortNames: ["Jim", "Pam"]
// ⇒ longNames: ["Michael", "Dwight", "Ryan"]
const [evenLength, oddLength] = partition(names, n => n.length % 2 === 0)
// ⇒ evenLength: ["Dwight", "Ryan"]
// ⇒ oddLength: ["Michael", "Jim", "Pam"]// an array we want to split into two arrays based on a condition
const names = ["Michael", "Jim", "Dwight", "Pam", "Ryan"]
// accepts array and function returning `true` or `false` for each element
const partition = (array, callback) => {
const matches = []
const nonMatches = []
// push each element into array depending on return value of `callback`
array.forEach(element => (callback(element) ? matches : nonMatches).push(element))
return [matches, nonMatches]
}
// destructure matches as `shortNames` and non-matches as `longNames`
const [shortNames, longNames] = partition(names, name => name.length <= 3)
// ⇒ shortNames: ["Jim", "Pam"]
// ⇒ longNames: ["Michael", "Dwight", "Ryan"]
const [evenLength, oddLength] = partition(names, n => n.length % 2 === 0)
// ⇒ evenLength: ["Dwight", "Ryan"]
// ⇒ oddLength: ["Michael", "Jim", "Pam"]// an array we want to split into two arrays based on a condition
const names = ["Michael", "Jim", "Dwight", "Pam", "Ryan"]
// accepts array and function returning `true` or `false` for each element
const partition = (array, callback) => {
const matches = []
const nonMatches = []
// push each element into array depending on return value of `callback`
array.forEach(element => (callback(element) ? matches : nonMatches).push(element))
return [matches, nonMatches]
}
// destructure matches as `shortNames` and non-matches as `longNames`
const [shortNames, longNames] = partition(names, name => name.length <= 3)
// ⇒ shortNames: ["Jim", "Pam"]
// ⇒ longNames: ["Michael", "Dwight", "Ryan"]
const [evenLength, oddLength] = partition(names, n => n.length % 2 === 0)
// ⇒ evenLength: ["Dwight", "Ryan"]
// ⇒ oddLength: ["Michael", "Jim", "Pam"]// an array we want to split into two arrays based on a condition
const names = ["Michael", "Jim", "Dwight", "Pam", "Ryan"]
// accepts array and function returning `true` or `false` for each element
const partition = (array, callback) => {
const matches = []
const nonMatches = []
// push each element into array depending on return value of `callback`
array.forEach(element => (callback(element) ? matches : nonMatches).push(element))
return [matches, nonMatches]
}
// destructure matches as `shortNames` and non-matches as `longNames`
const [shortNames, longNames] = partition(names, name => name.length <= 3)
// ⇒ shortNames: ["Jim", "Pam"]
// ⇒ longNames: ["Michael", "Dwight", "Ryan"]
const [evenLength, oddLength] = partition(names, n => n.length % 2 === 0)
// ⇒ evenLength: ["Dwight", "Ryan"]
// ⇒ oddLength: ["Michael", "Jim", "Pam"]