How to check if a string contain specific words?

Question

$a = 'how are you';
if (strpos($a,'are') !== false) {
    echo 'true';
}

In PHP, we can use the code above to check if a string contain specific words, but how can I do the same function in JavaScript/jQuery?

Answer 1

you can use indexOf for this

var a = 'how are you';
if (a.indexOf('are') > -1) {
  return true;
} else {
  return false;
}

Edit: This is an old answer that keeps getting up votes every once in a while so I thought I should clarify that in the above code, the if clause is not required at all because the expression itself is a boolean. Here is a better version of it which you should use,

var a = 'how are you';
return a.indexOf('are') > -1;

Update in ECMAScript2016:

var a = 'how are you';
return a.includes('are');  //true

Answer 2

indexOf/includes should not be used for finding whole words:

A word (in western culture) is a drawing of a symbols close to each other, with some space between each word. A word is considered as such if it's a complete piece of characters draw together and not a partial part of it:

"has a word".indexOf('wor')  // 6 ("wor" is not a word in this sentence)
"has a word".includes('ha') // true ("ha" is not a word in this sentence)

---

Check if a single word (whole word) is in the string

Find a real whole word, not just if the letters of that word are somewhere in the string.

const wordInString = (s, word) => new RegExp('\\b' + word + '\\b', 'i').test(s);

// tests
[
  '',            // true
  ' ',           // true
  'did',         // true
  'id',          // flase
  'yo ',         // flase
  'you',         // true
  'you not'      // true
].forEach(q => console.log(
  wordInString('dID You, or did you NOt, gEt WHy?', q) 
))

console.log(
  wordInString('did you, or did you not, get why?', 'you') // true
)

Check if all words are in the string

var stringHasAll = (s, query) => 
  // convert the query to array of "words" & checks EVERY item is contained in the string
  query.split(' ').every(q => new RegExp('\\b' + q + '\\b', 'i').test(s)); 


// tests
[
  '',            // true
  ' ',           // true
  'aa',          // true
  'aa ',         // true
  ' aa',         // true
  'd b',         // false
  'aaa',         // false
  'a b',         // false
  'a a a a a ',  // false
].forEach(q => console.log(
  stringHasAll('aA bB cC dD', q) 
))

Answer 3

If you are looking for exact words and don't want it to match things like "nightmare" (which is probably what you need), you can use a regex:

/\bare\b/gi

\b = word boundary
g = global
i = case insensitive (if needed)

If you just want to find the characters "are", then use indexOf.

If you want to match arbitrary words, you have to programatically construct a RegExp (regular expression) object itself based on the word string and use test.

Answer 4

You're looking for the indexOf function:

if (str.indexOf("are") >= 0){//Do stuff}

Answer 5

You might wanna use include method in JS.

var sentence = "This is my line";
console.log(sentence.includes("my"));
//returns true if substring is present.

PS: includes is case sensitive.

Answer 6

In javascript the includes() method can be used to determines whether a string contains particular word (or characters at specified position). Its case sensitive.

var str = "Hello there."; 

var check1 = str.includes("there"); //true
var check2 = str.includes("There"); //false, the method is case sensitive
var check3 = str.includes("her");   //true
var check4 = str.includes("o",4);   //true, o is at position 4 (start at 0)
var check5 = str.includes("o",6);   //false o is not at position 6

Answer 7

An easy way to do it to use Regex match() method :-

For Example

var str ="Hi, Its stacks over flow and stackoverflow Rocks."

// It will check word from beginning to the end of the string

if(str.match(/(^|\W)stack($|\W)/)) {

        alert('Word Match');
}else {

        alert('Word not found');
}

Check the fiddle

NOTE: For adding case sensitiveness update the regex with /(^|\W)stack($|\W)/i

Thanks

Answer 8

This will

/\bword\b/.test("Thisword is not valid");

return false, when this one

/\bword\b/.test("This word is valid");

will return true.

Answer 9

var str1 = "STACKOVERFLOW";
var str2 = "OVER";
if(str1.indexOf(str2) != -1){
    console.log(str2 + " found");
}

Answer 10

Using a conditional ternary operator

str = 'I am on StackOverflow';
str.match(/(^|\W)StackOverflow($|\W)/) ? 'Found. Why lie?' : 'Not Found';

Answer 11

If you'd like to find a single word in a string without regular expressions, you can do as follows:

function isWordInString(needle, haystack) {
  return haystack
    .split(' ')
    .some(p => (p === needle));
}
isWordInString('hello', 'hello great world!'); // true
isWordInString('eat', 'hello great world!'); // false

Advantages over regex:

• Works with non-latin characters like Hebrew
• No need to sanitize the word you search in the string. Some methods in other answers will fail and return a false positive when searching for a "." (dot)