How to check whether a given string is already present in an array or list in JavaScript?

Question

Possible Duplicates:
Javascript - array.contains(obj)
Best way to find an item in a JavaScript Array ?

I want to check, for example, for the word "the" in a list or map. Is there is any kind of built in function for this?

Answer 1

In javascript you have Arrays (lists) and Objects (maps).

The literal versions of them look like this:

var mylist = [1,2,3]; // array
var mymap = { car: 'porche', hp: 300, seats: 2 }; // object

if you which to figure out if a value exists in an array, just loop over it:

for(var i=0,len=mylist.length;i<len;i++) {
  if(mylist[i] == 2) {
     //2 exists
     break;
   }
}

if you which to figure out if a map has a certain key or if it has a key with a certain value, all you have to do is access it like so:

if(mymap.seats !== undefined) {
  //the key 'seats' exists in the object
}

if(mymap.seats == 2) {
  //the key 'seats' exists in the object and has the value 2
}

Answer 2

Array.indexOf(element) returns -1 if element is not found, otherwise returns its index