Without more information it is difficult to determine what your problem is exactly.
However, the most obvious thing that would result in erroneous charts is the use of:
for(a in data){
to parse the JSON object, which is actually an array, that has been returned by the AJAX success:function:
$.ajax({
success:function(data){
To quote the "for...in" page on MDN:
Array iteration and for...in
Note: for..in should not be used to iterate over an Array where index order is important.
Array indexes are just enumerable properties with integer names and are otherwise identical to general Object properties. There is no guarantee that for...in will return the indexes in any particular order and it will return all enumerable properties, including those with non–integer names and those that are inherited.
Because the order of iteration is implementation dependent, iterating over an array may not visit elements in a consistent order. Therefore it is better to use a for loop with a numeric index (or Array.forEach or the for...of loop) when iterating over arrays where the order of access is important.
Order is important in this instance because you should desire the presentation of the charts to be in the same order no matter the browser being used. Thus, you should process the members of the array in a deterministic manner.
More importantly:
Iterating over own properties only
If you only want to consider properties attached to the object itself, and not its prototypes, use getOwnPropertyNames or perform a hasOwnProperty check (propertyIsEnumerable can also be used). Alternatively, if you know there won't be any outside code interference, you can extend built-in prototypes with a check method.
Each array has properties which are associated with its prototype instead of just the members of the array. Including these in your processing, by use of the for(a in data){}, without any qualification, is almost guaranteed to result in an erroneous display.
One alternate method to code what you have is to use forEach():
$.ajax({
url:'http://localhost/mijson.php',
dataType:'json',
async:false,
success:function(data){
data.forEach(function(curObject, a) {
var div_pintar = "<div id='divgrafica"+a+"' class='myChart'></div>";
$("#espacio_graficas").append(div_pintar);
var datos_tmp = [];
datos_tmp.push(['Ok',data[a]['ok']]);
datos_tmp.push(['Fail',data[a]['fail']]);
$.jqplot('divgrafica'+a, [datos_tmp], {
title:data[a]['label'] ,
seriesDefaults:{
renderer:$.jqplot.PieRenderer,
trendline:{ show: true },
},
legend:{ show: true }
});
...
Note: I would normally change all the data[a] references to curObject, but not doing so will work (the array index is passed in as a) and results in the least amount of changes to your code. Making the additional changes should make the code slightly faster due to not having to do the array look-up multiple times.
With those changes and using the more descriptive index instead of a, the code looks like:
$.ajax({
url:'http://localhost/mijson.php',
dataType:'json',
async:false,
success:function(data){
data.forEach(function(curObject, index) {
var div_pintar = "<div id='divgrafica"+index+"' class='myChart'></div>";
$("#espacio_graficas").append(div_pintar);
var datos_tmp = [];
datos_tmp.push(['Ok',curObject['ok']]);
datos_tmp.push(['Fail',curObject['fail']]);
$.jqplot('divgrafica'+index, [datos_tmp], {
title:curObject['label'] ,
seriesDefaults:{
renderer:$.jqplot.PieRenderer,
trendline:{ show: true },
},
legend:{ show: true }
});
...
