Using Jquery to get JSON objects from local file
I'm trying to get a list of JSON objects (products) from a local file using Jquery and store all the objects in a single array called allItems. The file is co-located in the same directory as th开发者_运维问答e code, and it's called "allItems.json". Here's how I'm doing it now:
function getAllSupportedItems(){
var allItems = new Array();
$.getJSON("allItems.json",
function(data){
$.each(data.items,
function(item){
allItems.push(item);
});
});
return allItems;
}
Based on this example: http://api.jquery.com/jQuery.getJSON/
For getAllSupportedItems
to be able to return any items, the AJAX call needs to run synchronously.
getJSON
translates to the following asynchronous call:
$.ajax({
url: url,
dataType: 'json',
data: data,
success: callback
});
Asynchronous is the default. You therefore need to explicitly change your request to a synchronous one:
$.ajax({
url: url,
dataType: 'json',
data: data,
success: callback,
async: false
});
An alternative is to rethink the way you use getAllSupportedItems
and make it into an asynchronous utility:
function getAllSupportedItems(callback){
$.getJSON("allItems.json",
function(data){
var allItems = [];
$.each(data.items,
function(item){
allItems.push(item);
});
callback(allItems);
// callback(data.items); should also work
});
}
Update
When I initially wrote this answer, jQuery didn't have built-in Deferred support. It is a lot more concise and flexible to do something like this today:
function getAllSupportedItems( ) {
return $.getJSON("allItems.json").then(function (data) {
return data.items;
});
}
// Usage:
getAllSupportedItems().done(function (items) {
// you have your items here
});
How are you using this? If you're expecting the main function ("getAllSupportedItems") to return the array you make, well that won't work. The $.getJSON
function is asynchronous, and so the handler won't actually build the array until after the outer function has returned.
精彩评论