jQuery loop over JSON string $.each example
Review a simple jQuery example to loop over a JavaScript array object.
var json = [ {"id":"1","tagName":"apple"}, {"id":"2","tagName":"orange"}, {"id":"3","tagName":"banana"}, {"id":"4","tagName":"watermelon"}, {"id":"5","tagName":"pineapple"} ]; $.each(json, function(idx, obj) { alert(obj.tagName); });
Above code snippet is working fine, prompts the “apple”, “orange” … as expected.
Problem : JSON string
Review below example, declares a JSON string (enclosed with single or double quotes) directly.
var json = '[{"id":"1","tagName":"apple"},{"id":"2","tagName":"orange"}, {"id":"3","tagName":"banana"},{"id":"4","tagName":"watermelon"}, {"id":"5","tagName":"pineapple"}]'; $.each(json, function(idx, obj) { alert(obj.tagName); });
In Chrome, it shows following errors in console :
Uncaught TypeError: Cannot use 'in' operator to search for '156' in [{"id":"1","tagName":"apple"}...
Solution : Convert JSON string to JavaScript object
To fix it, converts it to Javascript object via standard JSON.parse() or jQuery $.parseJSON.
var json = '[{"id":"1","tagName":"apple"},{"id":"2","tagName":"orange"}, {"id":"3","tagName":"banana"},{"id":"4","tagName":"watermelon"}, {"id":"5","tagName":"pineapple"}]'; $.each(JSON.parse(json), function(idx, obj) { alert(obj.tagName); }); //or $.each($.parseJSON(json), function(idx, obj) { alert(obj.tagName); });
Most web applications will return JSON formatted string directly, you need to convert it to JavaScript object before parse it with jQuery.
References