Effectively Search for set of substrings in a string Javascript

Question

I currently have a string and set of substrings/search strings which I want to effectively search in the given string. This is what I have currently:

const apple = "apple"
const banana = "banana"
const chickoo = "chickoo"
const dates = "dates"
const eggplant = "eggplant"
const default = "default"

let string = "foobar" // This String changes dynamically
if (string.includes(apple)){
    return apple;
} else if (string.includes(banana)) {
    return banana;
} else if (string.includes(chickoo)) {
    return chickoo;
} else if (string.includes(dates)) {
    return dates;
} else if (string.includes(eggplant)) {
    return eggplant;
} else {
    return default;
}

This approach works, however I am looking for a more compact and efficent way of searching for substrings in a given string.

Edit: I am currently using the following way:

const fruits = ["apple", "banana", "chickoo", "dates", "eggplant"];
let string = "foobar" //This is dynamic
for(let fruit in fruits) {
    if(string.includes(fruits[fruit])){
        return fruits[fruit];
    }
}
return "default";

Let me know if there is even more effective way to do this than the above one.

search/match for the regular expression: /(apple)|(banana)|(chickoo)|(dates)|(eggplant)|(default)/g — ControlAltDel
– ControlAltDel, Commented Feb 2, 2022 at 16:37
It looks to me like a find... return fruits.find(f => string.includes(fruit)); — danh
– danh, Commented Feb 2, 2022 at 16:55
Define effective? Less code / more performant / something else? — Jamiec
– Jamiec, Commented Feb 2, 2022 at 16:55

maraaaaaaaa · Accepted Answer · 2022-02-02 17:02:54Z

2

Using Regex:

function matchFruit(input) {
    const match = input.match(/apple|banana|chickoo|dates|eggplant|default/);
    if(match)
        return match[0];
    return "default";
}

Note

this will only return the first matching fruit in the string. So "foobarapplebanana" will return "apple". If instead you want to return an array of strings, [ "apple", "banana" ], then return match instead of match[0].

Test Here

edited Feb 2, 2022 at 17:02

answered Feb 2, 2022 at 16:53

maraaaaaaaa

8,2013 gold badges25 silver badges42 bronze badges

Sign up to request clarification or add additional context in comments.

4 Comments

dkellner Over a year ago

This is actually better than the replace I did

Dext1232 Over a year ago

This seems to be super ccol. But I had one doubt, what is faster: RegEx match or String finds(includes or filter)?

maraaaaaaaa Over a year ago

@Dext1232 you'd just have to test and benchmark for yourself. But what I can tell you is that Regex would provide you a forward-only search. Whereas if you did a String.includes for each fruit, it would have to re-iterate the entire string for each fruit you search for.

dkellner Over a year ago

Regex beats search-over-and-over approach because it only looks for the whole stuff in one round.

JaivBhup · Accepted Answer · 2022-02-02 16:55:15Z

1

You can use filter()

let string = "foobar" //This is dynamic
var matchingFruits =  fruits.filter(fruit=>string.includes(fruit))
return matchingFruit.length>0?matchingFruit[0]:"default"

answered Feb 2, 2022 at 16:55

JaivBhup

8655 silver badges8 bronze badges

2 Comments

Jamiec Over a year ago

may as well just use find which does the same without having to check the length of an array

JaivBhup Over a year ago

Yes right this is just if you need to find all the elements which are included in string.

jesmoava9 · Accepted Answer · 2022-02-02 16:52:43Z

0

You can check these includes in one line.

First you have to create the available list and then check it. If it was not found in the list, default is returned.

const apple = "apple"
const banana = "banana"
const chickoo = "chickoo"
const dates = "dates"
const eggplant = "eggplant"
const default = "default"

let string = "foobar" // This String changes dynamically

const availableFruits = [apple, banana, chickoo, dates, egplant]

return availableFruits.includes(string) ? string : default;

answered Feb 2, 2022 at 16:52

jesmoava9

693 bronze badges

1 Comment

danh Over a year ago

I think the OP is checking the other way round: does string contain any of the fruits

dkellner · Accepted Answer · 2022-02-03 20:35:28Z

-1

Simple case

If you only have a couple of words, you can compose a regular expression - either go with match (see accepted answer), or if you go for simplicity, you can even just reduce the whole string to the word found inside:

found = string.replace(/.*(apple|banana|cherry).*/,"$1")

This will find the last one, btw. Again, string.match() is better, I just don't want to steal @maksymiuk's solution. Regex is faster than multiple straight searches because it only iterates over the string once, looking for all possible candidates.

Now if we're optimizing, let's consider another case:

Look for many words

If there are many search strings (like a whole dictionary) and you only have a relatively short text, a reverse approach could be more efficient. Build a list of words you have, and check them against an object that has the dictionary words as keys.

function searchManyWordsInText(text,wordList) {
    let wordLookup = {};
    for(let w of wordList) wordLookup[w] = 1;
    let textWords = text.split(/\s+/);
    for(let x of textWords) if(wordLookup[x]) return x;
    return false;
}

//  test it:

searchManyWordsInText(
    'this is a banana championship',
    ['apple','banana','cherry']
);

//  returns 'banana', the first word found

edited Feb 3, 2022 at 20:35

answered Feb 2, 2022 at 16:54

dkellner

10.2k3 gold badges55 silver badges53 bronze badges

1 Comment

dkellner Over a year ago

I'm amazed by people who downvote everyone else just to be on top of the list.

Collectives™ on Stack Overflow

Effectively Search for set of substrings in a string Javascript

4 Answers 4

Note

4 Comments

2 Comments

1 Comment

Simple case

Look for many words

1 Comment

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

4 Answers 4

Note

4 Comments

2 Comments

1 Comment

Simple case

Look for many words

1 Comment

Your Answer

Sign up or log in

Post as a guest

Related