How to write a function to pass 2 tests

Question

I am learning and practicing writing test with javascript:

Here is the test cases find.test.js :

var findTheNeedle = require("./find-needle");

test("Find the needle", function () {
  var words = ["house", "train", "slide", "needle", "book"];
  var expected = 3;

  var output = findTheNeedle(words, "needle");

  expect(output).toEqual(expected);
});

test("Find the plant", function () {
  var words = ["plant", "shelf", "arrow", "bird"];
  var expected = 0;

  var output = findTheNeedle(words, "plant");

  expect(output).toEqual(expected);
});

Here is my following function find.js :

function findNeedle(words) {
  for (var i = 0; i < words.length; i++) {
    if (words[i] === "needle") {
      var needle = i;
    }
  }

  return needle;
}
module.exports = findNeedle;

Answer 1

You should do this:

var findTheNeedle = require("./find-needle");

test("Find the object", function () {
  var words = ["house", "train", "slide", "needle", "book"];
  var expected = 3;

  var output = findTheNeedle(words, "needle");

  expect(output).toEqual(expected);

  var words = ["plant", "shelf", "arrow", "bird"];
  var expected = 0;

  var output = findTheNeedle(words, "plant");

  expect(output).toEqual(expected);
});

Bit I think you need to remake the function, like this:

function findInArray( arr, word ) {
  let index = -1
  for (var i = 0; i < arr.length; i++) {
    if (arr[i] === word) {
       index = i;
    }
  }

  return index;
}
module.exports = findInArray;

If any of "expects" fails, all the test will fail

Answer 2

It seems your function will return the index of a "word" in a list of words. This means, your function has to receive 2 variables as parameters: "word" and "words".

I think the current function name (and filename) - findNeedle is not "correct", so I recommended changing it. How about findWordIndex ?

The function logic is simple, you can use Array.indexOf utility to do it, or do it in your way.

module.exports = (words, word) => words.indexOf(word);

Or

module.exports = (words, word) => {
  for (let i = 0; i < words.length; i++) {
    if (words[i] === word) {
      return i; // stop right after you found it
    }
  }
  return -1;
};