CODEWITHSUNDEEP
javascriptarrays
anna
anna

Reputation: 1149

javascript filter method doesnt return one result

I have a filter's method on array, where I have a symbols of regions. Then I would like to equal to my results from HTTP request. When result is true it should console.log("profile"), when false, should return console.log("rejected"). But regardless of the result, there is always console.log("profile")

 .getProfile(id, token)
    .then(data => {
      let data = data.data;
      let regions = ["SP", "RS", "PR", "MG", "SC"];
   if (
        regions.filter(reg => {
          console.log(reg);
          console.log(data.region === reg);
          return reg === data.region; // it is false, because data.region is AC
        })
      ) {
        console.log("profile");
      } else console.log("rejected");
    })

So in console my result are: enter image description here

So.. I am wondering, why, when reg === data.region is false, I have console.log("profile). It should be rejected. Any hint where the error lies?

Upvotes: 0

Views: 1354

Answers (6)

Saurabh Yadav
Saurabh Yadav

Reputation: 3386

let regions = ["SP", "RS", "PR", "MG", "SC"];

let result = regions.filter(a => a === 'AC');

It give you to blank array which is not a falsy value

so thats why if condition run...

You can use The some() method tests whether at least one element in the array passes the test implemented by the provided function. It returns a Boolean value.

  let regions = ["SP", "RS", "PR", "MG", "SC"];

let result = regions.some(a => a === 'AC');
// or you can use `includes`
let result1 = regions.includes('AC'); 

now result contain a boolean value

You can do like this i refactor your code

.getProfile(id, token)
    .then(data => {
      let data = data.data;
      let regions = ["SP", "RS", "PR", "MG", "SC"];
      let result = regions.some(reg =>  reg === data.region);  // it is false, because data.region is AC
    if (result) {
        console.log("profile");
      } else  {

      }console.log("rejected");
    })

Upvotes: 3

Nidin Vinayakan
Nidin Vinayakan

Reputation: 1227

filter will always return an array. In your case, if condition is always truthy because an empty array [] is truthy. Instead of filter use find this will return undefined if nothing matched, which is falsy.

.getProfile(id, token)
.then(data => {
  let data = data.data;
  let regions = ["SP", "RS", "PR", "MG", "SC"];
  if (
    regions.find(reg => reg === data.region)
  ) {
    console.log("profile");
  } else console.log("rejected");
})

Upvotes: 1

Cid
Cid

Reputation: 15257

In addition to the other answers, if you don't need to use the filtered array but to log rejected or profile, I'd use .some() instead of .filter()

const regions = ["SP", "RS", "PR", "MG", "SC"];
const toFind = "foo";

if (regions.some(reg => {
          console.log(reg);
          console.log(toFind === reg);
          return toFind === reg;}))
{
  console.log("profile");
}
else
  console.log("rejected");

Upvotes: 1

StepUp
StepUp

Reputation: 38209

You can use includes method:

if (regions.includes('AC')) {

}

or you can check length of filtered array:

let length = regions.filter(reg => {
          console.log(reg);
          console.log(data.region === reg);
          return reg === data.region;
        }).length;

if (length) {
}

Upvotes: 1

Jamiec
Jamiec

Reputation: 136239

It boils down to an empty array evaluating truthy 

if([])
  console.log("Empty arrays are truthy");

Fix it by checking the length

if([].length)
   console.log("You wont see this.")

0 is falsey!

Upvotes: 1

MysterX
MysterX

Reputation: 2378

filter method returns array, and if no matches, it returns an empty array. Even if array is empty it interpreted as true

Upvotes: 1

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