#

# Example: 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.

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().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 step will add a new object member while leaving the original
            // intact (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 = x.toFixed(2); // added to item
                return v.toFixed(2); // 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.one('#demo_go').on('click', function (e) {
        // Disable the button temporarily
        this.set('disabled',true);

        // Store the requested currency
        var sel = Y.one("#demo select");
        example.currency = sel.get("options").item(sel.get("selectedIndex")).get("value");

        // Send the request for the JSON data
        Y.io('../assets/json/json-convert-values-response.json',{
            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.one('#demo_go').set('disabled',false);
                    }
                },
                failure : function () {
                    alert("Error getting inventory data");
                }
            }
        });
    });

    }); // End YUI(..).use(..,function (Y) {

## Complete Example Source

    <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="BRL">Brazilian Real</option>
            <option value="GBP">British Pound</option>
            <option value="CAD">Canadian Dollar</option>
            <option value="CNY">Chinese Yuan</option>
            <option value="COP">Colombian Peso</option>
            <option value="HRK">Croatian Kuna</option>
            <option value="CZK">Czech Koruna</option>
            <option value="DKK">Danish Krone</option>
            <option value="EEK">Estonian Kroon</option>
            <option value="EUR">Euro</option>
            <option value="HKD">Hong Kong Dollar</option>
            <option value="HUF">Hungarian Forint</option>
            <option value="ISK">Iceland Krona</option>
            <option value="INR">Indian Rupee</option>
            <option value="JPY">Japanese Yen</option>
            <option value="KRW">Korean Won</option>
            <option value="LVL">Latvian Lat</option>
            <option value="LTL">Lithuanian Lita</option>
            <option value="MYR">Malaysian Ringgit</option>
            <option value="MXN">Mexican Peso</option>
            <option value="NZD">New Zealand Dollar</option>
            <option value="NOK">Norwegian Krone</option>
            <option value="PHP">Philippine Peso</option>
            <option value="PLN">Polish Zloty</option>
            <option value="RUB">Russian Rouble</option>
            <option value="SGD">Singapore Dollar</option>
            <option value="SKK">Slovak Koruna</option>
            <option value="ZAR">South African Rand</option>
            <option value="LKR">Sri Lanka Rupee</option>
            <option value="SEK">Swedish Krona</option>
            <option value="TRY">Turkey Lira</option>
            <option value="USD" selected="selected">U.S. Dollar</option>
            <option value="CHF">Swiss Franc</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>

    <script>
    YUI().use("node", "io", "json-parse",function (Y) {

    // Safari 4.0.3's native JSON does not support adding members during parse,
    // so use JavaScript implementation for consistency
    Y.JSON.useNativeParse = false;

    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',

        convert : function (k,v) {
            // 'this' will refer to the object containing the key:value pair,
            // so this step will add a new object member while leaving the original
            // intact (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 = x.toFixed(2); // added to item
                return v.toFixed(2); // assigned to item.Price
            }
            return v;
        },

        updateTable : function (inventory) {
            // Update the column header
            Y.one('#demo table th span').set('innerHTML',example.currency);

            var tbody = Y.one('#demo table tbody'),
                html  = ['<table><tbody>'],
                rowTemplate = '<tr><td>{SKU}</td><td>{Item}</td><td>{Price}</td><td>{convertedPrice}</td></tr>',
                i, len;

            if (inventory) {
                for (i = 0, len = inventory.length; i < len; ++i) {
                    html.push(Y.Lang.sub(rowTemplate, inventory[i]));
                }
            } else {
                html.push('<tr><td colspan="4">No Inventory data</td></tr>');
            }

            html.push('</tbody></table>');

            tbody.replace(Y.Node.create(html.join('')).one('tbody'));
        }
    };

    Y.one('#demo_go').on('click', function (e) {
        // Disable the button temporarily
        this.set('disabled',true);

        // Store the requested currency
        var sel = Y.one("#demo select");
        example.currency = sel.get("options").item(sel.get("selectedIndex")).get("value");

        Y.io('../assets/json/json-convert-values-response.json',{
            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.one('#demo_go').set('disabled',false);
                    }
                },
                failure : function () {
                    alert("Error getting inventory data");
                }
            }
        });
    });

    // Expose example objects for inspection
    YUI.example = example;
    });
    </script>