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# YUI Library Examples: JSON: Adding new object members during parsing

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## JSON: Adding new object members during parsing

This example shows how to use the `reviver` parameter in `JSON.parse` to add new object members and format existing members during the parsing phase.

View example in new window.

Choose a currency, then get the data

Inventory
SKU | Item | Price (USD) | Price (USD)
--- | --- | --- | ---
Click Get Data

### The data

The data returned from the server will be a JSON string containing this object structure:

[ {"SKU":"23-23874", "Price":23.99, "Item":"Helmet"}, {"SKU":"48-38835", "Price":14.97, "Item":"Football"}, {"SKU":"84-84848", "Price":3.49, "Item":"Goggles"}, {"SKU":"84-84843", "Price":183, "Item":"Badminton Set"}, {"SKU":"84-39321", "Price":6.79, "Item":"Tennis Balls"}, {"SKU":"39-48949", "Price":618, "Item":"Snowboard"}, {"SKU":"99-28128", "Price":78.99, "Item":"Cleats"}, {"SKU":"83-48281", "Price":4.69, "Item":"Volleyball"}, {"SKU":"89-32811", "Price":0.59, "Item":"Sweatband"}, {"SKU":"28-22847", "Price":779.98, "Item":"Golf Set"}, {"SKU":"38-38281", "Price":8.25, "Item":"Basketball Shorts"}, {"SKU":"82-38333", "Price":1.39, "Item":"Lip balm"}, {"SKU":"21-38485", "Price":0.07, "Item":"Ping Pong ball"}, {"SKU":"83-38285", "Price":3.99, "Item":"Hockey Puck"} ]

### Create a reviver function

We'll contain all the moving parts in an `example` namespace. In it, we'll include the currency exchange rates and a function to reference the rates to add a new member to the JSON response as it is being parsed.

YUI({base:"../../build/", timeout: 10000}).use("node", "io", "json-parse",function (Y) { var example = { rates : {"USD":1,"EUR":0.6661,...,"COP":2000 ,"ARS":3.1289}, currency : 'USD', // updated by the select element convert : function (k,v) { // 'this' will refer to the object containing the key:value pair, // so this will add a new object member while leaving the original // in tact (but formatted to two decimal places). If the original // is not needed, just return the converted value. if (k === 'Price') { var x = Math.round(v * example.rates[example.currency] * 100) / 100; this.convertedPrice = example.formatCurrency(x); // added to item return example.formatCurrency(v); // assigned to item.Price } return v; }, ... }; ...

### Sending the request and parsing the JSON response

When the Get Data button is clicked, we send an `io` request for the JSON data, and in our success handler, pass our conversion function to `JSON.parse` with the response text. The resulting inventory records will have an additional member, `convertedPrice`. This data is then passed to a UI method to update the inventory table.

Y.get('#demo_go').on('click', function (e) { // Disable the button temporarily this.set('disabled',true); // Store the requested currency var sel = Y.get("#demo select"); example.currency = sel.get("options").item(sel.get("selectedIndex")).get("value"); // Send the request for the JSON data Y.io('assets/data.php',{ timeout : 3000, on : { success : function (xid, res) { var inventory; try { inventory = Y.JSON.parse(res.responseText,example.convert); example.updateTable(inventory); } catch(e) { alert("Error getting inventory data"); } finally { Y.get('#demo_go').set('disabled',false); } }, failure : function () { alert("Error getting inventory data"); } } }); }); }); // End YUI(..).use(..,function (Y) {

### Example markup

<div id="demo"> <p>Choose a currency, then get the data</p> <select> <option value="ARS">Argentine Peso</option> <option value="AUD">Australian Dollar</option> ... <option value="TWD">Taiwan Dollar</option> <option value="THB">Thai Baht</option> </select> <input type="button" id="demo_go" value="Get Data"> <table cellspacing="0"> <caption>Inventory</caption> <thead> <tr> <th>SKU</th> <th>Item</th> <th>Price (USD)</th> <th>Price (<span>USD</span>)</th> </tr> </thead> <tbody> <tr><td colspan="4">Click <em>Get Data</em></td></tr> </tbody> </table> </div>

### Full Code Listing

Below is the full source for the example, including the functions responsible for formatting the price and updating the UI.

YUI({base:"../../build/", timeout: 10000}).use("node", "io", "json-parse",function (Y) { var example = { rates : {"USD":1,"EUR":0.6661,"GBP":0.5207,"AUD":1.1225,"BRL":1.609,"NZD":1.4198,"CAD":1.0667,"CHF":1.0792,"CNY":6.8587 ,"DKK":4.9702,"HKD":7.8064,"INR":42.0168,"JPY":109.8901,"KRW":1000,"LKR":107.5269,"MXN":10.1317,"MYR" :3.3167,"NOK":5.3277,"SEK":6.2617,"SGD":1.4073,"THB":33.7838,"TWD":31.1526,"VEF":2.1445,"ZAR":7.6923 ,"BGN":1.3028,"CZK":16.0514,"EEK":10.4275,"HUF":158.7302,"LTL":2.2999,"LVL":0.4692,"PLN":2.1758,"RON" :2.3804,"SKK":20.2429,"ISK":4.8008,"HRK":81.3008,"RUB":24.3309,"TRY":1.1811,"PHP":44.2478,"COP":2000 ,"ARS":3.1289}, currency : 'USD', formatCurrency : function (amt) { amt += amt % 1 ? "0" : ".00"; return amt.substr(0,amt.indexOf('.')+3); }, convert : function (k,v) { // 'this' will refer to the object containing the key:value pair, // so this will add a new object member while leaving the original // in tact (but formatted to two decimal places). If the original // is not needed, just return the converted value. if (k === 'Price') { var x = Math.round(v * example.rates[example.currency] * 100) / 100; this.convertedPrice = example.formatCurrency(x); // added to item return example.formatCurrency(v); // assigned to item.Price } return v; }, updateTable : function () { // Update the column header Y.get('#demo table th span').set('innerHTML',example.currency); var tbl = Y.get('#demo table'), html = ["<tbody>"],i,j = 1,l,item; if (example.inventory) { for (i = 0, l = example.inventory.length; i < l; ++i) { item = example.inventory[i]; html[j++] = '<tr><td>'; html[j++] = item.SKU; html[j++] = '</td><td>'; html[j++] = item.Item; html[j++] = '</td><td>'; html[j++] = item.Price; html[j++] = '</td><td>'; html[j++] = item.convertedPrice; html[j++] = '</td></tr>'; } } else { html[j++] = '<tr><td colspan="4">No Inventory data</td></tr>'; } html[j] = "</tbody>"; tbl.replaceChild(Y.Node.create(html.join('')),tbl.query('tbody')); } }; Y.get('#demo_go').on('click', function (e) { // Disable the button temporarily this.set('disabled',true); // Store the requested currency var sel = Y.get("#demo select"); example.currency = sel.get("options").item(sel.get("selectedIndex")).get("value"); Y.io('assets/data.php',{ timeout : 3000, on : { success : function (xid, res) { var inventory; try { inventory = Y.JSON.parse(res.responseText,example.convert); example.updateTable(inventory); } catch(e) { alert("Error getting inventory data"); } finally { Y.get('#demo_go').set('disabled',false); } }, failure : function () { alert("Error getting inventory data"); } } }); }); // Expose example objects for inspection YUI.example = example; });

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