Using indexOf to filter an array

Question

I am trying to output the first two objects in the events array using indexOf.

This doesn\'t return anything:

var whiteList=[\'css\',\'js\'];

var          


        

Answer 1

You are doing it wrong, it should go like this.

var whiteList = ['css', 'js'];

var events = [{
  file: 'css/style.css',
  type: 'css'
}, {
  file: 'js/app.js',
  type: 'js'
}, {
  file: 'index/html.html',
  type: 'html'
}];

var fileList = events.filter(function(event) {
  return whiteList.indexOf(event.type) > -1
})

console.log(fileList)

Answer 2

With ES6, you could use Set for faster access with larger data sets.

var whiteList = ['css', 'js'],
    whiteSet = new Set(whiteList),
    events = [{ file: 'css/style.css', type: 'css' }, { file: 'js/app.js', type: 'js' }, { file: 'index/html.html', type: 'html' }],
    fileList = events.filter(event => whiteSet.has(event.type));

console.log(fileList);