Use toLowerCase() on a string array - Angularjs 5, Typescript

Question

I’m trying to transform an array with strings inside in lowercase using toLowerCase, but it doesn’t seem to work with an array, but only with a string... How do I fix it?

items: Array<{tag: string[], image: string, page}>;

toggledItems() {
  this.items = [
      {
          tag: ['exemplo1','exemplo2'],
          image: '../../assets/imgs/exemplo/ccc.jpg',
          page: Ex1Page,
      },
      {
          tag: ['exemplo4', 'exemplo5', 'exemplo6'],
          image: '../../assets/imgs/exemplo/ci.jpg',
          page: Ex1Page,
      }
  ];
}

In the code below is where I add the "tag" array that is inside the "items" array. But it doesn’t work.

if (val && val.trim() != '') {
  this.items = this.items.filter((item) => {
    return (item.tag.toLowerCase().indexOf(val.toLowerCase()) > -1);
  })
}

Answer 1

Just iterate through the object array and map each tag.

if (val && val.trim() != '') {
  for(item of items) {
    item.tag = item.tag.map(res => res.toLowerCase());
  }
}

In order to be able to filter the tags so that it is not necessary to write the whole word to find the desired array, it is interesting to use the javascript some function. Basically it will work as a find, but it just finds an element that meets the requirement to return true.

Follow the plunker: http://plnkr.co/edit/reGXZfiyBBY7GXZT81hG