Paulos3000 - 2 months ago 4x

Javascript Question

Doing this 'Hamming' test on Exercism, and I'm struggling to see what's wrong with my function - would appreciate if someone could shed some light:

`it('small hamming distance in longer strand', function () {`

expect(hamming.compute('GGACG', 'GGTCG')).toEqual(1);

});

For every character that doesn't match between the two strings sequentially, I want to add 1. So in this case, G===G (0), G===G (0), A!==T (1), C===C (1), G===G (1).

So, as indicated in the spec, I would expect

However my function below returns

`this.compute = function(dna1, dna2) {`

var mismatches = 0;

for (var i = 0; i <= dna1.length; i++) {

if (dna1[i] === dna2[i]) {

mismatches ++;

}

}

return mismatches;

}

Can anyone explain where I'm going wrong?

Thanks in advance!

Answer

If you expect difference, you function should be like :

```
this.compute = function(dna1, dna2) {
var mismatches = 0;
for (var i = 0; i <= dna1.length; i++) {
if (dna1[i] != dna2[i]) {//if character not equals
mismatches ++;
}
}
return mismatches;
}
```

Source (Stackoverflow)

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