Home » Jquery » How do I check if string contains substring? [duplicate]

How do I check if string contains substring? [duplicate]

Posted by: admin November 2, 2017 Leave a comment

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This question already has an answer here:

Answers:

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))

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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.

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Another way:

var testStr = "This is a test";

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

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

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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.

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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);
    };
}

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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.

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Returns number of times the keyword is included in the string.

var count = "I have one keyword".match(/keyword/g);
var clean_count = !count ? false : count.length;

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I know that best way is str.indexOf(s) !== -1; http://hayageek.com/javascript-string-contains/

I suggest another way(str.replace(s1, "") !== str):

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

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You can also check if the exact word is contained in a string. E.g.:

function containsWord(haystack, needle) {
    return (" " + haystack + " ").indexOf(" " + needle + " ") !== -1;
}

Usage:

containsWord("red green blue", "red"); // true
containsWord("red green blue", "green"); // true
containsWord("red green blue", "blue"); // true
containsWord("red green blue", "yellow"); // false

This is how jQuery does its hasClass method.

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

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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.

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you can define an extension method and use it later.

String.prototype.contains = function(it) 
{ 
   return this.indexOf(it) != -1; 
};

so that you can use in your page anywhere like:

var str="hello how are you";
str.contains("are");

which returns true.

Refer below post for more extension helper methods.
Javascript helper methods

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None of the above worked for me as there were blank spaces but this is what I did

tr = table.getElementsByTagName("tr");

    for (i = 0; i < tr.length; i++) {
        td = tr[i].getElementsByTagName("td")[0];
        bottab.style.display="none";
        bottab2.style.display="none";
        if (td) {
        var getvar=td.outerText.replace(/\s+/, "") ;

            if (getvar==filter){
                tr[i].style.display = "";
            }else{
                tr[i].style.display = "none";
            }

        }
    }