4

<div id="dynamicTable" columns="26,40,41,21,71,39,23,19"> 

var columns = $('#dynamicTable').attr('columns');
var attributeIds = new Array();
attributeIds = columns.split(',');

This creates an array of strings, I need them to be ints. What's the best way to do this?

Mark
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    changelog answer is no doubt the most elegant possible, but depending on what you need to do with those integers maybe you can do it directly in the `map` function instead of storing the new array in separate variable. – Shadow The GPT Wizard Dec 27 '10 at 16:38
  • Thanks! Did the best I could with the amount of information that was given to me :-) – changelog Dec 27 '10 at 16:43
  • both changelog and patrick dw work, which is better / faster? – Mark Dec 27 '10 at 16:49
  • Both are equally good. Speed isn't an issue here, since it's so fast the difference would be negligible. My only concern in regards to $.parseJSON, as far as I know, is that if you don't include the json2.js library, some older browsers don't implement the native JSON parsing functionality, which has only been around since Dec 2009. – changelog Dec 27 '10 at 17:03
  • Nevermind the previous comment. jQuery creates a new function with a body of 'return ' + data, which is essentially the same as eval() when the browser can't do native JSON parsing. – changelog Dec 27 '10 at 17:06
  • [In this test](http://jsperf.com/parsejson-vs-map-to-convert-string-to-ints/2), among the browsers I tested, `eval()` is fastest by far, `$.map()` is next, then `$.parseJSON`. – user113716 Dec 27 '10 at 17:11
  • I added a `while` loop solution to my answer, which seems to give the best overall performance [in this test](http://jsperf.com/parsejson-vs-map-to-convert-string-to-ints/2). – user113716 Dec 27 '10 at 17:26
  • Kudos on the perf test, btw. Great job. Didn't know about that site. – changelog Dec 27 '10 at 18:53

2 Answers2

9

You could use $.parseJSON.

Example: http://jsfiddle.net/ULkXy/

var columns = $('#dynamicTable').attr('columns');
var attributeIds = $.parseJSON( '[' + columns + ']' );

Here's another way using a while loop with the unary + operator:

Example: http://jsfiddle.net/ULkXy/1/

var columns = $('#dynamicTable').attr('columns');
var attributeIds = columns.split(',');
var len = attributeIds.length;

while( len-- ) {
    attributeIds[len] = +attributeIds[len];
}
user113716
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  • Problem with that last solution is that it inverts the order of the ids. What if the ids need to be sent in a specific order? – changelog Dec 27 '10 at 18:51
  • @changelog: It doesn't invert the order. It just iterates through the array in reverse. If there are 10 items, index 9 is overwritten by a modified value of index 9. Then 8, 7, 6, etc.. If you click the example link I provided, you'll see that the result in the `alert()` has the same order as that in the `columns` attribute. – user113716 Dec 27 '10 at 20:15
7
var columns = $('#dynamicTable').attr('columns'),
    attributeIds = $.map(columns.split(','), function(val, idx) { return parseInt(val, 10) });
changelog
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