JQuery $. each traverses JavaScript Array object instances

JQuery $. each traverses JavaScript Array object instances

View a simple jQuery example to traverse 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);});

The code snippet above works normally and prompts "apple", "orange "... As expected.
Question: JSON string

In the following example, a json string (with a single or double quotation mark) is declared 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 displays errors in the console:

Uncaught TypeError: Cannot use 'in' operator to search for '000000'
In [{id: 1, tagName: apple }...

Solution: convert a JSON string to a JavaScript Object.
To fix it, convert it to a JavaScript Object through standard JSON. parse () or jQuery's $. 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);});