查看一个简单的jQuery的例子来遍历一个JavaScript数组对象。
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); });
上面的代码片断工作正常,提示 “apple”, “orange” … 等,如预期一样。
问题: JSON 字符串
下面的例子中,声明了一个JSON字符串(随附单或双引号)直接地。
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); });
在Chrome中,它显示在控制台下面的错误:
Uncaught TypeError: Cannot use 'in' operator to search for '156'
in [{"id":"1","tagName":"apple"}...
解决方案:JSON字符串转换为JavaScript对象。
要修复它,通过标准JSON.parse()或jQuery 的 $.parseJSON 将其转换为JavaScript对象。
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); });