I have an array like this:
var movies = [
{ Name: "The Red Violin", ReleaseYear: "1998", Director: "François Girard" },
{ Name: "Eyes Wide Shut", ReleaseYear: "1999", Director: "Stanley Kubrick" },
{ Name: "The Inheritance", ReleaseYear: "1976", Director: "Mauro Bolognini" }
];
I want to find the location of the movie that's released in 1999.
Should return 1.
What's the easiest way?
Thanks.
You will have to iterate through each value and check.
for(var i = 0; i < movies.length; i++) {
if (movies[i].ReleaseYear === "1999") {
// i is the index
}
}
Since JavaScript has recently added support for most common collection operations and this is clearly a filter operation on a collection, instead you could also do:
var moviesReleasedIn1999 = movies.filter(function(movie) {
return movie.ReleaseYear == "1999";
});
assuming you're not interested in the indexes but the actual data objects. Most people aren't anyways :)
.filter is not supported in all browsers, but you can add it yourself to your code base:
https://developer.mozilla.org/en/JavaScript/Reference/Global_Objects/Array/filter#Compatibility
break; at the end, before closing the if. PS: Great avatar!
return i; if it is a function. (in addition to my previous comment)
Built in? Use loops.
You want to get fancy? Linq to Javascript: http://jslinq.codeplex.com/
Something like:
function findMovieIndices(movies, prop, value) {
var result = [];
for(var i = movies.length; i--; ) {
if(movies[i][prop] === value) {
result.push(i); // personally I would return the movie objects
}
}
return result;
}
Usage:
var indices = findMovieIndices(movies, "ReleaseYear", "1999");
Maybe this gives you some idea for a more generalized function (if you need it).
Since you've also tagged it with jQuery, you could use the 'map' function:
var movies = $.map(movies,function(item,index){
return item.ReleaseYear == 1999 ? index : null;
});
This will return an array of indexes for all movies with the year of 1999. If you wanted the movies themselves as an array:
var movies = $.map(movies,function(item){
return item.ReleaseYear == 1999 ? item : null;
});
null or undefined is returned then it will insert that into the resulting array.
If functional style programming is applicable:
_.indexOf(_.pluck(movies, "ReleaseYear"), "1999")
Because it's that simple. The functional toolkit that is underscore.js can be very powerful.
You'll have to create your own searching function.
Array.prototype.findMovieByYear = function (findYear) {
for (var i = 0; i < this.length; i++) {
// this actually returns the element, maybe you just want
// to return the array index ( the i param )
if (this[i].Release == findYear) return this[i];
}
return null;
// or return -1 or whatever if you want to return the index
};
// now you can call:
movies.findMovieByYear('1998');
// and that should return
{ Name: "The Red Violin", ReleaseYear: "1998", Director: "François Girard" }
Of course, this way of doing it actually affects every array you create.. which is maybe not what you want.. you can create your own array object then ...
for in loops and breaks various 3rd party libraries. At least put a disclaimer on it.
for...in for arrays anyway ;) But yes, I remember a problem with jQuery and extended Object or Array prototype...