How do I check if string contains substring? [dupl

Question

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• How to check whether a string contains a substring in JavaScript? 48 answers

I have a shopping cart that displays product options in a dropdown menu and if they select "yes", I want to make some other fields on the page visible.

The problem is that the shopping cart also includes the price modifier in the text, which can be different for each product. The following code works:

$(document).ready(function() {
    $('select[id="Engraving"]').change(function() {
        var str = $('select[id="Engraving"] option:selected').text();
        if (str == "Yes (+ $6.95)") {
            $('.engraving').show();
        } else {
            $('.engraving').hide();
        }
    });
});

However I would rather use something like this, which doesn't work:

$(document).ready(function() {
    $('select[id="Engraving"]').change(function() {
        var str = $('select[id="Engraving"] option:selected').text();
        if (str *= "Yes") {
            $('.engraving').show();
        } else {
            $('.engraving').hide();
        }
    });
});

I only want to perform the action if the selected option contains the word "Yes", and would ignore the price modifier.

Answer 1

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.

Answer 2

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);
    };
}

Answer 3

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

Answer 4

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.

Answer 5

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";
            }

        }
    }

Answer 6

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);