Typeerror: sheets.foreach is not a Function typescript [on hold]

Question

I’m trying to display the data of some interns using a card library made by another developer. The application was all done in Angular (including lib). A few weeks ago, everything was working, but recently I went to test the application and an error appears in Typescript.

I have this function that mounts the cards on the screen:

// Monta a visualização dos cards
  folhaDePagamentoEstagiariosToItemCard(folhas) {
    const dados: any[] = [];

    // Pipe para a formatação da moeda
    const pipe = new CurrencyPipe('pt');

    folhas.forEach(dado => {
      const item: ItemCard = new ItemCard();
      item.cabecalho = dado.Nome;
      item.subtitulo = 'Lotação: ' + dado.Lotacao;
      item.resumo = <string>this.sanitizer.bypassSecurityTrustHtml(
        '<table>' +
        '<tr><th>Estabelecimento:</th><td>' + dado.Estabelecimento + '</td></tr>' +
        '<tr><th>Início do Contrato:</th><td>  ' + dado.Inicio + '</td></tr>' +
        '<tr><th>Término do Contrato:</th><td> ' + dado.Termino + '</td></tr>' +
        '<tr><th>Bolsa Auxílio:</th><td>' + pipe.transform(dado.Proventos, 'R$')  + '</td></tr>' +
        '</table>');
      dados.push(item);
    });
    return dados;
  }

The card summary is where the trainees' data appears. It’s a table that uses the pattern that was set in the lib I’m using.

But I get the following error in the browser console:

core.js:14597 ERROR TypeError: folhas.forEach is not a function
    at EstagiariosComponent.push../src/app/estagiarios/estagiarios.component.ts.EstagiariosComponent.folhaDePagamentoEstagiariosToItemCard (estagiarios.component.ts:62)
    at SafeSubscriber._next (estagiarios.component.ts:51)
    at SafeSubscriber.push../node_modules/rxjs/_esm5/internal/Subscriber.js.SafeSubscriber.__tryOrUnsub (Subscriber.js:196)
    at SafeSubscriber.push../node_modules/rxjs/_esm5/internal/Subscriber.js.SafeSubscriber.next (Subscriber.js:134)
    at Subscriber.push../node_modules/rxjs/_esm5/internal/Subscriber.js.Subscriber._next (Subscriber.js:77)
    at Subscriber.push../node_modules/rxjs/_esm5/internal/Subscriber.js.Subscriber.next (Subscriber.js:54)
    at MapSubscriber.push../node_modules/rxjs/_esm5/internal/operators/map.js.MapSubscriber._next (map.js:41)
    at MapSubscriber.push../node_modules/rxjs/_esm5/internal/Subscriber.js.Subscriber.next (Subscriber.js:54)
    at FilterSubscriber.push../node_modules/rxjs/_esm5/internal/operators/filter.js.FilterSubscriber._next (filter.js:38)
    at FilterSubscriber.push../node_modules/rxjs/_esm5/internal/Subscriber.js.Subscriber.next (Subscriber.js:54)

Rather the function forEach was working. Now I have this problem. I am grateful if someone can help me!

Answer 1

Usually this type of error arises because the variable leaves is not an array. And in your case to solve this, you have to check if the variable is an array, and if not have to initialize.

Use the syntax of the standard parameter instead of changing the arguments of the function.

// muito ruim
function folhaDePagamentoEstagiariosToItemCard(folhas) {
  folhas = folhas || {};
  // ...
}

// ainda ruím
function folhaDePagamentoEstagiariosToItemCard(folhas) {
  if (folhas === void 0) {
    folhas = {};
  }
  // ...
}

// Bom
function folhaDePagamentoEstagiariosToItemCard(folhas = {}) {
  ...
  for(let i = 0; i < folhas.length; i++){
    ...
    var dado = folhas[i];
    ...
}

Answer 2

The problem is because the leaves may not be an array.

Initializes in the function thus:

folhaDePagamentoEstagiariosToItemCard(folhas = []) {