Internet Explorer (7/8) fails to loop through javascript array

Question

I need to replace accented characters in a string with their unaccented counterparts and I implemented this http://lehelk.com/2011/05/06/script-to-remove-diacritics/.

var defaultDiacriticsRemovalMap = [
            {'base':'A', 'letters':/[\u0041\u24B6\uFF21\u00C0\u00C1\u00C2\u1EA6\u1EA4\u1EAA\u1EA8\u00C3\u0100\u0102\u1EB0\u1EAE\u1EB4\u1EB2\u0226\u01E0\u00C4\u01DE\u1EA2\u00C5\u01FA\u01CD\u0200\u0202\u1EA0\u1EAC\u1EB6\u1E00\u0104\u023A\u2C6F]/g},   
            /* ... 
            so on and so forth
            .... */
        ];

        var changes;
        function removeDiacritics (str) {
            if(!changes) {
                changes = defaultDiacriticsRemovalMap;
            }
            for(var i=0; i<changes.length; i++) {
                str = str.replace(changes[i].letters, changes[i].base);
            }
            return str.replace(/\s+/g, '_'); //space to dash
        }

This fails in IE 7 and 8 (works in every other browser) with the error 'changes[...].letters' is null or not an object on the line str = str.replace(changes[i].letters, changes[i].base);, and I have no idea why. I mean, I understand that the browser thinks that it had encountered a null value, but I fail to see how can this be the case.

I copied my code to a jsfiddle (it fires the same error there as well) so you can take a look at it.

http://jsfiddle.net/GggcU/

user1236048 · Accepted Answer · 2012-03-22 09:48:50Z

3

I'm not sure that this is you problem as you don't have your whole code pasted, but I know for sure that IE7/8 throws an error if you add an extra comma after your last element of an array.

So if you have something like this:

var defaultDiacriticsRemovalMap = [
 {'base':'A'},   
 {'k1':'v1'},
 ...
 {'k_last':'v_last'}, // this last comma will break your js in IE7/8
];

answered Mar 22, 2012 at 9:48

user1236048

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1 Comment

RobG Over a year ago

It doesn't "break" arrays, IE incorrectly treats it as an elision and adds one to the length. It will throw an error in an object literal because it's a syntax error in ES 3.

RobG · Accepted Answer · 2012-03-22 09:59:16Z

2

Almost certainly you have a trailing comma in the array. IE treats it as an elision and adds one to the length, effectively adding an extra (undefined) member. Other browsers correctly ignore it. In any case, remove it.

Just to show how IE treats the comma:

var a = [0,1,];

alert(a.length); // 3 in IE, 2 in others

alert(a.hasOwnProperty('2')); // false in all browsers

The trailing comma isn't an elision, two trailing commas are required for that.

edited Mar 22, 2012 at 9:59

answered Mar 22, 2012 at 9:52

RobG

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Comments

otakustay · Accepted Answer · 2012-03-22 09:49:23Z

1

You have an extra comma (,) before your array's closing bracket (]), IE7/8 then add an extra undefined value to this array, so when loop using for iteration, IE7/8 would encounter a value of undefined at index of 84 (try to log changes.length and see difference)

answered Mar 22, 2012 at 9:49

otakustay

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1 Comment

RobG Over a year ago

Strictly, it increases the length by one, there is no extra element. But attempting to read a non-existant property has the same result (it returns undefined).

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