How to compare only first character of 2 strings (javascript)?

Question

Trying to write a javascript function for comparing only first character of 2 strings but can't make it work. Here is the code.

function compare(wordOne, wordTwo) {
    if (wordOne.substring(0) === wordTwo.substring(0))
    {
        return true;
    } else {
        return false;
    }
}
compare("house", "hell");

What is your code trying to achieve? You want to compare only first chaaracter? — gurvinder372
– gurvinder372, Commented Apr 27, 2018 at 12:30
developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/… with .substring() you have the option to include where the substring starts and ends (if end is omitted, it will capture to the end of the string)... wordOne.substring(0,1) — Doug
– Doug, Commented Apr 27, 2018 at 12:33
Yes sorry i didn't explain it really nice...but yes i only need to compare first character. — nitring
– nitring, Commented Apr 27, 2018 at 12:34
You can also treat strings as arrays of characters. str = "hello" means that str[1] = e — TheCrzyMan
– TheCrzyMan, Commented Apr 27, 2018 at 12:35

JanS · Accepted Answer · 2018-04-27 12:44:58Z

5

Assuming you want to compare the first letter of the two strings, you can use the following code

function compare(wordOne, wordTwo) {
    return wordOne[0] === wordTwo[0];
}
compare("house", "hell");

This condenses the if/else condition, as you are just interested in whether the first letters are equal - not in how different they are. You can also use str.toUpperCase() (or) str.toLowerCase() in order to make the comparison case insensitive.

As per @Josh Katofsky's suggestion, you can of course make this function more versatile by - for instance - adding a third parameter that tests the n-th letter:

function compare(wordOne, wordTwo, index) {
    return wordOne[index] === wordTwo[index];
}
compare("house", "hell", 0);

edited Apr 27, 2018 at 12:44

answered Apr 27, 2018 at 12:31

JanS

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1 Comment

Josh Katofsky Over a year ago

It would help make the code more reusable if you passed an index into the function and then returned wordOne[index] === wordTwo[index]

Chris Brown · Accepted Answer · 2018-04-27 12:32:10Z

4

To explain why your current code doesn't work, you need to pass a second parameter to .substring as the to value. String.substring(0) just returns the whole string after the 0th character, so the entire word. Fixed example;

function compare(wordOne, wordTwo) {
    if (wordOne.substring(0, 1) === wordTwo.substring(0, 1)) {
        return true;
    }
    else 
    {
        return false;
    }
}

compare("house", "hell");

You could also just use wordOne[0] === wordTwo[0]

answered Apr 27, 2018 at 12:32

Chris Brown

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Comments

gurvinder372 · Accepted Answer · 2018-04-27 12:39:05Z

2

substring returns the part of the string between the start and end indexes, or to the end of the string.

If you want to compare only first character, use charAt

function compare(wordOne, wordTwo) {
   return wordOne.charAt(0) === wordTwo.charAt(0);
}
compare("house", "hell");

Or you can pass the index as the parameter

function compare(wordOne, wordTwo, index) {
   return wordOne.charAt(index) === wordTwo.charAt(index);
}
compare("house", "hell", 0);

edited Apr 27, 2018 at 12:39

answered Apr 27, 2018 at 12:34

gurvinder372

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1 Comment

KarelG Over a year ago

you have luck that javascript is nice for the developer so that your second example would work as intended :P (add extra arg for clarity)

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