Parse JSON in Ext JS 4 or JavaScript
This question already has an answer here:
Have a look at http://docs.sencha.com/ext-js/4-1/#!/api/Ext.JSON. There you find how you can parse JSON with Ext JS 4.
var strJson = '{"value": [{"idProductCategoryAttributeValue":43,"value":"7","sortOrder":0}]}';
var obj = Ext.JSON.decode(strJson);
var obj = Ext.decode(jsonstr);