CODEWITHSUNDEEP
javascriptarrays
Fred J.
Fred J.

Reputation: 6029

converting a for loop to array filter

This javascript code tries to use the array.filter for better performance instead of the for loop "I guess". Any way, the results are not the same, when it was expected to be. It tries to find out the names of students who are included in the searchWords array.
Any ideas why?thx

let searchWords = ['john','matt','marry'];
let students = ['matt','jack'];
let names = [];
for (let i = 0; i < searchWords.length; i++) {
   if (students.indexOf(searchWords[i]) !== -1) {
       names.push(searchWords[i]);
   }
}
console.log(names.length); // => 1 "correct"

names = [];
names = searchWords.filter(x => students.filter(y => students.indexOf(x) !== -1));
console.log(names.length); // => 3 "incorrect"

Upvotes: 1

Views: 291

Answers (1)

James Wesc
James Wesc

Reputation: 81

The filter line has essentially added another loop. It should be

names = searchWords.filter(x => students.indexOf(x) !== -1);

Upvotes: 5

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