%%[ set @JSON = HttpGET("http://some-url-that-returns-json") ]%%

<script runat="server">
    Platform.Load("Core", "1")
    // get JSON from ampscript
    var jsonObj = Variable.GetValue("@JSON");
    var evaluatedJSON = eval("(" + jsonObj + ")");
</script>

%%[

var @Json
set @Json = '[{"name": "john doe","email": "john.doe@mail.com"},{"name": "jane doe","email": "jane.doe@mail.com"}]'

]%%
{{.dataobject JsonVar type=variable source=@Json maxrows=20}}
     {{.data}}
          {"target":"@Json"}
     {{/data}}
{{/dataobject}}
{{#each JsonVar}}
  <br><br>Name: {{name}}
  <br>Email: {{email}}
{{/each}}

Name: john doe
Email: john.doe@mail.com

Name: jane doe
Email: jane.doe@mail.com

"[{"name":"john doe","email":"john.doe@mail.com"},{"name":"jane doe","email":"jane.doe@mail.com"}]"

%%[
   var @json
   set @json = AttributeValue("Recipient_List")
]%%

{{.dataobject JsonVar type=variable source=@json maxrows=20}}
   {{.data}}
        {"target":"@Json"}
   {{/data}}
{{/dataobject}}
{{#each JsonVar}}
   <p>{{name}}, {{email}}</p>
{{/each}}

<script runat="server">
     var str = '{ "prop1": "propVal" }';
     var obj = Platform.Function.ParseJSON(str);
     var val = obj.prop1;
</script>