Как найти определенное слово в тексте javascript

asked Aug 13, 2010 at 21:25

Like this:

if (str.indexOf("Yes") >= 0)

…or you can use the tilde operator:

if (~str.indexOf("Yes"))

This works because indexOf() returns -1 if the string wasn’t found at all.

Note that this is case-sensitive.
If you want a case-insensitive search, you can write

if (str.toLowerCase().indexOf("yes") >= 0)

Or:

if (/yes/i.test(str))

The latter is a regular expression or regex.

Regex breakdown:

• / indicates this is a regex
• yes means that the regex will find those exact characters in that exact order
• / ends the regex
• i sets the regex as case-insensitive
• .test(str) determines if the regular expression matches str
  To sum it up, it means it will see if it can find the letters y, e, and s in that exact order, case-insensitively, in the variable str

You could use search or match for this.

str.search( 'Yes' )

will return the position of the match, or -1 if it isn’t found.

answered Aug 13, 2010 at 21:29

It’s pretty late to write this answer, but I thought of including it anyhow. String.prototype now has a method includes which can check for substring. This method is case sensitive.

var str = 'It was a good date';
console.log(str.includes('good')); // shows true
console.log(str.includes('Good')); // shows false

To check for a substring, the following approach can be taken:

if (mainString.toLowerCase().includes(substringToCheck.toLowerCase())) {
    // mainString contains substringToCheck
}

Check out the documentation to know more.

answered May 7, 2016 at 13:38

Another way:

var testStr = "This is a test";

if(testStr.contains("test")){
    alert("String Found");
}

** Tested on Firefox, Safari 6 and Chrome 36 **

ECMAScript 6 introduces String.prototype.includes, previously named contains.

It can be used like this:

'foobar'.includes('foo'); // true
'foobar'.includes('baz'); // false

It also accepts an optional second argument which specifies the position at which to begin searching:

'foobar'.includes('foo', 1); // false
'foobar'.includes('bar', 1); // true

It can be polyfilled to make it work on old browsers.

answered Apr 16, 2016 at 23:00

The includes() method determines whether one string may be found within another string, returning true or false as appropriate.

Syntax :-string.includes(searchString[, position])

searchString:-A string to be searched for within this string.

position:-Optional. The position in this string at which to begin searching for searchString; defaults to 0.

string = 'LOL';
console.log(string.includes('lol')); // returns false 
console.log(string.includes('LOL')); // returns true 

You can use this Polyfill in ie and chrome

if (!('contains' in String.prototype)) {
    String.prototype.contains = function (str, startIndex) {
        "use strict";
        return -1 !== String.prototype.indexOf.call(this, str, startIndex);
    };
}

answered Jul 3, 2013 at 14:09

If you are capable of using libraries, you may find that Lo-Dash JS library is quite useful. In this case, go ahead and check _.contains() (replaced by _.includes() as of v4).

(Note Lo-Dash convention is naming the library object _.
Don’t forget to check installation in the same page to set it up for your project.)

_.contains("foo", "oo");     // → true
_.contains("foo", "bar");    // → false
// Equivalent with:
_("foo").contains("oo");     // → true
_("foo").contains("bar");    // → false

In your case, go ahead and use:

_.contains(str, "Yes");
// or:
_(str).contains("Yes");

..whichever one you like better.

answered Oct 1, 2015 at 6:18

var str = "Hello World!", s1 = "ello", s2 = "elloo";
alert(str.replace(s1, "") !== str);
alert(str.replace(s2, "") !== str);

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asked Mar 22, 2011 at 8:18

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

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) 
))

answered Jan 12, 2014 at 23:41

Stephen ChungStephen Chung

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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

answered Oct 20, 2019 at 8:09

answered Sep 20, 2018 at 6:33

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