Answers for "reduce javescipt"

javascript reduce

/* reduce method: combine an array's values together, left to right */

let myArray = [1, 2, 3];

let a = myArray.reduce((initial, current) => initial + current, 0);
// [0 + 1 + 2 + 3] → 6

let b = myArray.reduce((initial, current) => initial + (current*10), 7);
// [7 + (1*10) + (2*10) + (3*10)] → 67

// Combine right to left with .reduceRight
let c = myArray.reduceRight((initial, current) => initial / current, 30);
// [30 / 3 / 2 / 1] → 5

/* Syntax: array.reduce((accumulator, currentValue) =>
combineFunction, accumulatorStartValue); */

js reduce

// Arrow function
reduce((previousValue, currentValue) => { ... } )
reduce((previousValue, currentValue, currentIndex) => { ... } )
reduce((previousValue, currentValue, currentIndex, array) => { ... } )
reduce((previousValue, currentValue, currentIndex, array) => { ... }, initialValue)

// Callback function
reduce(callbackFn)
reduce(callbackFn, initialValue)

// Inline callback function
reduce(function(previousValue, currentValue) { ... })
reduce(function(previousValue, currentValue, currentIndex) { ... })
reduce(function(previousValue, currentValue, currentIndex, array) { ... })
reduce(function(previousValue, currentValue, currentIndex, array) { ... }, initialValue)