Counting word occurrences in a string javascript

Question

I'm doing this little exercise where I'm trying to count the amount of word occurrences in my string theSentence.

const theSentence = "The quick brown fox jumps over the lazy brown dog, who thinks the world is flat and the sky\'s blue. The brown fox then goes to sleep";
let arr= theSentence.split(' ');

function findWord(word, arr){
    let count = 0;
    for(let i = 0; i < arr.length; i++){
        if(arr[i] === word){
            return count++;
        }
    }
    return console.log(word +": " + count);
}

My function is as follows

findWord(/fox/i, theSentence);

My expected output was supposed to be fox: 2

But my actual out puts was /fox/i: 0

Any pointers on what I might be doing wrong? My goal is to repeat this function so it reads the, fox, and brown

Any pointers? Thank You

Code Maniac · Answer 1 · 2019-03-10T06:48:20.500

2

You have several syntax problems in your code

/fox/i === arr[i] will never turns out to be true. because /fox/i is regex and arr[i] is having primitive strings.
return statement before count dosen't make any sense.
You're splitting theSentence outside of function and storing in arr, but in your function call you're passing theSentence only where it should be arr or use split inside function

const theSentence = "The quick brown fox jumps over the lazy brown dog, who thinks the world is flat and the sky\'s blue. The brown fox then goes to sleep";

function findWord(word, arr){
    arr= theSentence.split(' ');
    let count = 0;
    for(let i = 0; i < arr.length; i++){
        if(word.test(arr[i])){
            count++;
        }
    }
    return console.log(word +": " + count);
}

findWord(/fox/i, theSentence);

edited Mar 10 '19 at 06:48

answered Mar 10 '19 at 06:42

Code Maniac

37,143
5
39
60

I'm testing it on node and the `/gi` reg expression flag wasn't rendering properly, but your correction works when I use the '/i' regex. Why did you at the `/g` to the reg expressions? Thanks for the help! – Squirtle Mar 10 '19 at 06:52
@Squirtle `g` is a global flag used when you need to match more than one occurrences. but in this case it is not needed, my bad i placed it mistakenly,i already removed it – Code Maniac Mar 10 '19 at 06:53

Maheer Ali · Answer 2 · 2019-03-10T07:05:44.747

2

There are few problems:

You are using return count++ which will stop the further execution of function.Should remove return
You are comparing RegExp() to a string instead you should use test() method of RegExp()
You should return console.log(...) it will return undefined. You can return the value and then log it.

const theSentence = "The quick brown fox jumps over the lazy brown dog, who thinks the world is flat and the sky\'s blue. The brown fox then goes to sleep fox";
let arr= theSentence.split(' ');
function findWord(word, arr){
    let count = 0;
    for(let i = 0; i < arr.length; i++){
        if(word.test(arr[i])){
            count++;
        }
    }
    return word +": " + count
}
console.log(findWord(/fox/i, arr));

A better way to that is using String.prototype.match() and g flag in Regex. If you want to match the whole word fox use /fox ?/gi as regex. If you want to match it from inside word use /fox/gi

const theSentence = "The quick brown fox jumps over the lazy brown dog, who thinks the world is flat and the sky\'s blue. The brown fox then goes to sleep";
function findWord(word, str){
    return word + ": " + str.match(word).length
}
console.log(findWord(/fox/gi, theSentence));

edited Mar 10 '19 at 07:05

answered Mar 10 '19 at 06:49

Maheer Ali

35,834
5
42
73

The last code is wrong. just add `fox` at the end of see the result. i guess it's a typo an extra space – Code Maniac Mar 10 '19 at 07:01
You are right. Any suggestion for fix? – Maheer Ali Mar 10 '19 at 07:03
You can add an alternation `/fox ?/gi` – Code Maniac Mar 10 '19 at 07:04
@Code Maniac thanks it worked. But I don't think OP want to check for only whole words. – Maheer Ali Mar 10 '19 at 07:08
If you use match than you need to use either word boundaries `(\b)` or the one you have written now – Code Maniac Mar 10 '19 at 07:09

ellipsis · Answer 3 · 2019-03-10T06:55:14.000

1

Try this. Use filter to search the word in the array and return the count

const theSentence = "The quick brown fox jumps over the lazy brown dog, who thinks the world is flat and the sky\'s blue. The brown fox then goes to sleep";
let arr= theSentence.split(' ');

function findWord(word, arr){
    let count = 0;
    count=arr.filter(e=>e.toLowerCase()==word.toLowerCase()).length
    return word +": " + count;
}

console.log(findWord('the',arr))

edited Mar 10 '19 at 06:55

answered Mar 10 '19 at 06:41

ellipsis

12,049
2
17
33

It keeps returning `1` when the expected outcome is `2` – Squirtle Mar 10 '19 at 06:53
Check the edits – ellipsis Mar 10 '19 at 06:55

score 1 · Answer 4 · answered Mar 10 '19 at 06:41

The second parameter is named arr, which sounds like you meant to pass an array - if that's what you wanted, pass arr instead of theSentence:

/fox/i is a regular expression, which is an object, not a primitive - it will never be === to anything else. Call .test on each word in the array, on the regular expression, and increment count with count++, and don't return inside the loop - if you return, the function will terminate immediately. (you want it to iterate over all words in the array)

const theSentence = "The quick brown fox jumps over the lazy brown dog, who thinks the world is flat and the sky\'s blue. The brown fox then goes to sleep";
let arr= theSentence.split(' ');

function findWord(word, arr){
    let count = 0;
    for(let i = 0; i < arr.length; i++){
        if(word.test(arr[i])){
            count++;
        }
    }
    return console.log(word +": " + count);
}
findWord(/fox/i, arr);

You might consider using the pattern

/\bfox\b/i

instead - this will match the number of times fox exists in the input, case-insensitive, with a word boundary on each side.

const theSentence = "The quick brown fox jumps over the lazy brown dog, who thinks the world is flat and the sky\'s blue. The brown fox then goes to sleep";

function findWord(pattern, sentence){
  const count = sentence.match(pattern).length;
  return console.log(pattern +": " + count);
}
findWord(/\bfox\b/gi, theSentence);

prasanth · Answer 5 · 2019-03-10T06:51:50.983

1

You are passing Regex so use with pattern.test(str) .And i could rewrite code with simple format

const theSentence = "The quick brown fox jumps over the lazy brown dog, who thinks the world is flat and the sky\'s blue. The brown fox then goes to sleep";


function findWord(word, arr){
   arr= arr.split(' ');
   return arr.filter(a=> word.test(a)).length
}

console.log(findWord(/fox/i, theSentence));
console.log(findWord(/The/i, theSentence));

edited Mar 10 '19 at 06:51

answered Mar 10 '19 at 06:49

prasanth

22,145
4
29
53

1

There's a typo. i guess you meant `pattern.test(str)` not `pattern.text(str)` – Code Maniac Mar 10 '19 at 06:51

Counting word occurrences in a string javascript

5 Answers5