javascript : string contains ...

Question

How can I check if one string contains another substring in Javascript?

Usually I would expect a String.contains() method, but there doesn't seem to be one.

Edit : thanks for all the answers :) however it seems that I have another problem :(

when I use the ".indexof" method, Firefox refuses to start the javascript (this is for an extension).

My code is :

var allLinks = content.document.getElementsByTagName("a");

for (var i=0, il=allLinks.length; i<il; i++) {
   elm = allLinks[i];
   var test = elm.getAttribute("class");
   if (test.indexof("title")!=-1) {
    alert(elm);
    foundLinks++;
   }
  }
  if (foundLinks === 0) {
   alert("No title class found");
  }
  else {
   alert("Found " + foundLinks + " title class");
  }

Firefox doesn't display an alert box. This works if I get rid of the .indexof() method. I already tried something like if(test=="title")... but it didn't work.

Answer 1

var s = "foo";
alert(s.indexOf("oo") != -1);

indexOf returns the position of the string in the other string. If not found, it will return -1.

https://developer.mozilla.org/en/Core%5FJavaScript%5F1.5%5FReference/Objects/String/indexOf

Answer 2

var index = haystack.indexOf(needle);

Answer 3

Use regular expression

RegExp.test(string)

Answer 4

Javascript is case sensitive

indexOf()

not

indexof()

Answer 5

You need to call indexOf with a capital "O" as mentioned. It should also be noted, that in JavaScript class is a reserved word, you need to use className to get this data attribute. The reason it's probably failing is because it's returning a null value. You can do the following to get your class value...

var test = elm.getAttribute("className");
//or
var test = elm.className

Answer 6

I know your question is already answered, but I thought this might be helpful too.

You can easily add a contains method to String with this statement:

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

Answer 7

Hello,

You could use the javascript search() method

Syntax is: string.search(regexp)

it returns the position of the match, or -1 if no match is found.

See examples there: jsref_search

You don't need a complicated Regexp syntax, if you are not familiar with them a simple st.search("title") will do. If you want your test to be case insensitive, then you should do st.search(/title/i).