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optimizedRoute = ['Bengaluru', 'Salem', 'Erode', 'Tiruppur', 'Coimbatore'] result = [ {start: bengaluru, end: salem}, {start: salem, end: erode}, {start: erode, end: tiruppur}, {start: tiruppur, end: coimbatore}, ] I want to convert optimizedRoute to result. I want to do this with ES6 .reduce(). Here is what I've tried:
const r = optimizedRoute.reduce((places, place, i) => { const result: any = []; places = [] places.push({ startPlace: place, endPlace: place }); // result.push ({ startplace, endplace, seats: 4 }); // console.log(result); return places; }, {}); console.log(r) 
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Using the reduce method. The reduce() method executes a reducer function (a function that you provide as an argument) on each element of the array, resulting in a single output value. Here, the reducer function provided is concat() and the result is stored in an empty array.
reduce can use initial and return values of any type, which makes it very flexible. Let's explore how we can use it to perform some common tasks with plain objects.
The array reduce in JavaScript is a predefined method used to reduce an array to a single value by passing a callback function on each element of the array. It accepts a function executed on all the items of the specified array in the left-to-right sequence. The returned single value is stored in the accumulator.
To convert an array of objects to a Map , call the map() method on the array and on each iteration return an array containing the key and value. Then pass the array of key-value pairs to the Map() constructor to create the Map object.
You could use reduce for getting start and end part of the route and return the end for the next start.
getParts = a => ( // take a as array and return an IIFE r => ( // with an initialized result array a.reduce((start, end) => ( // reduce array by taking two values r.push({ start, end }), // push short hand properties end // and take the last value as start value for next loop )), r // finally return result ) )([]); // call IIFE with empty array const getParts = a => (r => (a.reduce((start, end) => (r.push({ start, end }), end)), r))([]); var optimizedRoute = ['Bengaluru', 'Salem', 'Erode', 'Tiruppur', 'Coimbatore'] console.log(getParts(optimizedRoute));.as-console-wrapper { max-height: 100% !important; top: 0; }@EDIT Grégory NEUT adding explaination
// Two thing to know first : // When no initial value is provided, // Array.reduce takes the index 0 as first value and start to loop at index 1 // Doing (x, y, z) // Will execute the code x, y and z // Equivalent to : // x; // y; // z; let ex = 0; console.log((ex = 2, ex = 5, ex = 3)); // So about the code const getParts = (a) => { // We are creating a new function here so we can have an array where to // push data to const func = (r) => { // Because there is no initial value // // Start will be the value at index 0 of the array // The loop is gonna start at index 1 of the array a.reduce((start, end) => { console.log(start, end); r.push({ start, end, }); return end; }); return r; }; return func([]); }; // Equivalent const getPartsEquivalent = (a) => { const r = []; // Because there is no initial value // // Start will be the value at index 0 of the array // The loop is gonna start at index 1 of the array a.reduce((start, end) => { console.log(start, end); r.push({ start, end, }); return end; }); return r; }; var optimizedRoute = ['Bengaluru', 'Salem', 'Erode', 'Tiruppur', 'Coimbatore'] console.log(getPartsEquivalent(optimizedRoute));.as-console-wrapper { max-height: 100% !important; top: 0; }If you love us? You can donate to us via Paypal or buy me a coffee so we can maintain and grow! Thank you!
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