converting an array back to an object in js code example

Example 1: convert array to object in javascript

const array =    [ [ 'cardType', 'iDEBIT' ],
      [ 'txnAmount', '17.64' ],
      [ 'txnId', '20181' ],
      [ 'txnType', 'Purchase' ],
      [ 'txnDate', '2015/08/13 21:50:04' ],
      [ 'respCode', '0' ],
      [ 'isoCode', '0' ],
      [ 'authCode', '' ],
      [ 'acquirerInvoice', '0' ],
      [ 'message', '' ],
      [ 'isComplete', 'true' ],
      [ 'isTimeout', 'false' ] ];
      
const obj = Object.fromEntries(array);
console.log(obj);

Example 2: how to convert an array into an object using javascript

// This function counts instances of elements in an array
// the return object has the array elements as keys
// and number of occurrences as it's value
const arrToInstanceCountObj = arr => arr.reduce((obj, e) => {
  obj[e] = (obj[e] || 0) + 1;
  return obj;
}, {});

arrToInstanceCountObj(['h', 'e', 'l', 'l', 'o', 'w', 'o', 'r', 'l', 'd'])
/*
  {
    h: 1,
    e: 1,
    l: 3,
    o: 2,
    w: 1,
    r: 1,
    d: 1,
  }
*/