Javascript Spread Operator Alternative

December 8, 2021

So I’m working with an old codebase that uses javascript es5, this means I cannot use the spread operator

          var listOfItems = [ ['item1', 'test', '1'], ['item2', 'test2', '2'] ];

          var docDefinition = 
          {
            style: 'piecesTable',
            table: {
              widths: ['*', '*', '*'],
              body: [
                [
                  {text: 'Reference', style: 'tableHeader'}, 
                  {text: 'Alias', style: 'tableHeader'},
                  {text: 'Type', style: 'tableHeader'},
                ],
                ...listOfItems
              ]
            }
          };

How can I spread "listOfItems" without using the spread operator as seen above ‘…listOfItems‘

The listOfItems should be spread out to two separate arrays so essentially the result should be:

          var docDefinition = 
          {
            style: 'piecesTable',
            table: {
              widths: ['*', '*', '*'],
              body: [
                [
                  {text: 'Reference', style: 'tableHeader'}, 
                  {text: 'Alias', style: 'tableHeader'},
                  {text: 'Type', style: 'tableHeader'},
                ],
                ['item1', 'test', '1'],
                ['item2', 'test2', '2']
              ]
            }
          };

>Solution :

You can use concat() to merge into your body array

     var listOfItems = [ ['item1', 'test', '1'], ['item2', 'test2', '2'] ];

      var docDefinition = 
      {
        style: 'piecesTable',
        table: {
          widths: ['*', '*', '*'],
          body: [
            [
              {text: 'Reference', style: 'tableHeader'}, 
              {text: 'Alias', style: 'tableHeader'},
              {text: 'Type', style: 'tableHeader'},
            ],
            
          ].concat(listOfItems)
        }
      };
      
      console.log(docDefinition)