How to check if a string contains text from an array of substrings in JavaScript?

Question

Pretty straight forward. In javascript, I need to check if a string contains any substrings held in an array.

Solution 1

There's nothing built-in that will do that for you, you'll have to write a function for it, although it can be just a callback to the some array method.

Two approaches for you:

• Array some method
• Regular expression

Array some

The array some method (added in ES5) makes this quite straightforward:

if (substrings.some(function(v) { return str.indexOf(v) >= 0; })) {
    // There's at least one
}

Even better with an arrow function and the newish includes method (both ES2015+):

if (substrings.some(v => str.includes(v))) {
    // There's at least one
}

Live Example:

const substrings = ["one", "two", "three"];
let str;

// Setup
console.log(`Substrings: ${substrings}`);

// Try it where we expect a match
str = "this has one";
if (substrings.some(v => str.includes(v))) {
    console.log(`Match using "${str}"`);
} else {
    console.log(`No match using "${str}"`);
}

// Try it where we DON'T expect a match
str = "this doesn't have any";
if (substrings.some(v => str.includes(v))) {
    console.log(`Match using "${str}"`);
} else {
    console.log(`No match using "${str}"`);
}

Regular expression

If you know the strings don't contain any of the characters that are special in regular expressions, then you can cheat a bit, like this:

if (new RegExp(substrings.join("|")).test(string)) {
    // At least one match
}

...which creates a regular expression that's a series of alternations for the substrings you're looking for (e.g., one|two) and tests to see if there are matches for any of them, but if any of the substrings contains any characters that are special in regexes (*, [, etc.), you'd have to escape them first and you're better off just doing the boring loop instead. For info about escaping them, see this question's answers.

Live Example:

const substrings = ["one", "two", "three"];
let str;

// Setup
console.log(`Substrings: ${substrings}`);

// Try it where we expect a match
str = "this has one";
if (new RegExp(substrings.join("|")).test(str)) {
    console.log(`Match using "${str}"`);
} else {
    console.log(`No match using "${str}"`);
}

// Try it where we DON'T expect a match
str = "this doesn't have any";
if (new RegExp(substrings.join("|")).test(str)) {
    console.log(`Match using "${str}"`);
} else {
    console.log(`No match using "${str}"`);
}

Solution 2

One line solution

substringsArray.some(substring=>yourBigString.includes(substring))

Returns true\false if substring exists\does'nt exist

Needs ES6 support

Solution 3

var yourstring = 'tasty food'; // the string to check against


var substrings = ['foo','bar'],
    length = substrings.length;
while(length--) {
   if (yourstring.indexOf(substrings[length])!=-1) {
       // one of the substrings is in yourstring
   }
}

Solution 4

function containsAny(str, substrings) {
    for (var i = 0; i != substrings.length; i++) {
       var substring = substrings[i];
       if (str.indexOf(substring) != - 1) {
         return substring;
       }
    }
    return null; 
}

var result = containsAny("defg", ["ab", "cd", "ef"]);
console.log("String was found in substring " + result);

Solution 5

For people Googling,

The solid answer should be.

const substrings = ['connect', 'ready'];
const str = 'disconnect';
if (substrings.some(v => str === v)) {
   // Will only return when the `str` is included in the `substrings`
}

View more solutions

Comments

[Martin Hennings]

Isn't there a map() function in the new HTML5-JavaScript-version? I remember having read something on that topic...

[T.J. Crowder]

@Martin: Good point, not map so much as some. some would help, but you'd have to pass it a function.

[kofifus]

or shorter: if (substrings.some(v => v===str)) {

[aamarks]

You kids...back when I was a kid we had to use these things called 'for' loops, and you had to use multiple lines and know whether your array was 1 or zero based, yeah...half the time you got it wrong and had to debug and look out for a little bugger called 'i'.

[fcrick]

Note that this is an answer to a slightly different question, which asks if a string contains text from an array of substrings. This code checks if a string is one of the substrings. Depends on what is meant by "contains" I suppose.

[Yunus Temurlenk]

please visit and check how to answer a question.

[Arti]

@YunusTemurlenk thnx

[GreySage]

Your first example doesn't need the len variable, just check i < arr.length.

[Avatar]

Plus it returns the first occurence of the word in the string, which is very helpful. Not only a true/false.

[Diyorbek Sadullaev]

Let's say we have a list of 100 substrings. Which way would be more efficient: RegExp or loop?

[Abid Khairy]

this is the cleanest answer here. many thanks!

[Ridhwaan Shakeel]

what is the es6 equivalent?

[Justin Farrugia]

the only answer that returns the matched array string. this should have been included in previous example for completeness sake

[Justin Farrugia]

the question here is not string in an array but strings in an array in a sentence