transactionAuthor.unshift is not a function code example

Example 1: unshift

//see https://developer.mozilla.org/fr/docs/Web/JavaScript/Reference/Objets_globaux/Array/unshift

const array1 = [1, 2, 3];

console.log(array1.unshift(4, 5));
// expected output: 5

console.log(array1);
// expected output: Array [4, 5, 1, 2, 3]

Example 2: .unshift

let monTableau = ['un', 'deux','trois', 'quatre'] ;
monTableau.unshift('zero') ; 
//console.log(monTableau) ;
 
 

 let monTableau2D = [
     ['Mark' , 'jeff' , 'Bill'] , 
     ['Zuckerberg' , 'Bezos' , 'Gates']
 ] ;
 monTableau2D[1].unshift('test') ; 
 //console.log(monTableau2D) ;