Load JSON data from html string

1. You can get the <script> tag using getElementById("data")
2. Check the CDATA Node by comparing with the constant XML_CDATA_SECTION_NODE.
3. Use str_replace() to remove the CDATA tag.
4. Use json_decode to parse your content to JSON.

By the way, the content inside your CDATA is actually a malformed JSON. It should be corrected as described below:

<![CDATA[
{
    "sortColumn" : "QuoteNumber",
    "quotes": {
        "Data":
        [
            {
                "ID":3235720,
                "Date":"20 May 2016",
                "QuoteNumber":"Q12415",
                "Name":"Some Name",
                "Client":"Some Client",
                "StateName":"Issued",
                "Url":"/Quote/View/3235720"
            }
        ]
    }
}
]]>

I have also added has_json_error() function at the bottom so that you could see some error messages.

$dom = new DOMDocument();
$dom->loadHTML($response);
$data = $dom->getElementById("data");
$content = ''; 
foreach ($data->childNodes as $child) { 
    if ($child->nodeType == XML_CDATA_SECTION_NODE) {
        $content = $child->textContent;
    }
}
$content = str_replace(array("<![CDATA[", "]]>"), '', $content);
$jsons = json_decode($content);

if(!has_json_error()) {
    echo $jsons->sortColumn;
    echo "<br /><br />";
    print_r($jsons->quotes);
    echo "<br /><br />";
    $data = $jsons->quotes->Data;
    foreach($data as $obj) {
        echo $obj->ID . "<br />";
        echo $obj->Date . "<br />";
        echo $obj->QuoteNumber . "<br />";
        echo $obj->Name . "<br />";
        echo $obj->Client . "<br />";
        echo $obj->StateName . "<br />";
        echo $obj->Url . "<br />";
    }
}

function has_json_error() {
    if (function_exists ( 'json_last_error' ) && json_last_error() !== JSON_ERROR_NONE) {
        switch (json_last_error()) {
            case JSON_ERROR_DEPTH:
                echo 'JSON_ERROR: - Maximum stack depth exceeded';
            break;
            case JSON_ERROR_STATE_MISMATCH:
                echo 'JSON_ERROR: - Underflow or the modes mismatch';
            break;
            case JSON_ERROR_CTRL_CHAR:
                echo 'JSON_ERROR: - Unexpected control character found';
            break;
            case JSON_ERROR_SYNTAX:
                echo 'JSON_ERROR: - Syntax error, malformed JSON';
            break;
            case JSON_ERROR_UTF8:
                echo 'JSON_ERROR: - Malformed UTF-8 characters, possibly incorrectly encoded';
            break;
            default:
                echo 'JSON_ERROR: - Unknown error: ' . json_last_error();
            break;
        }           
        return true;
    }
    else if (function_exists ( 'json_last_error_msg' ) && json_last_error_msg () !== "No error") {
        echo ("json_last_error_msg, JSON_ERROR:" . json_last_error_msg ());
        return true;
    }
    return false;
}

The result from the snippet above would be something like below:

QuoteNumber

stdClass Object ( 
    [Data] => Array ( 
        [0] => stdClass Object ( 
            [ID] => 3235720 
            [Date] => 20 May 2016 
            [QuoteNumber] => Q12415 
            [Name] => Some Name 
            [Client] => Some Client 
            [StateName] => Issued 
            [Url] => /Quote/View/3235720 
        ) 
    ) 
) 

3235720
20 May 2016
Q12415
Some Name
Some Client
Issued
/Quote/View/3235720