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javascriptobjectparsingobject-literal

Is this Javascript object literal key restriction strictly due to parsing?

Please refer to the code below, when I "comment in" either of the commented out lines, it causes the error (in IE) of "':' expected". So then is my conclusion correct, that this inability to provide a reference to an object value, as an object key in a string literal; is this strictly an interpreter/parsing issue? Is this a candidate for an awful (or at least "bad") "part" of Javascript, in contrast to Crockford's "good parts"?

<script>
var keys = {'ONE': 'one'};

//causes error:
//var obj1 = {keys.ONE: 'value1'};
//var obj1 = {keys['ONE']: 'value1'};

//works
var obj1 = {};
obj1[keys.ONE] = 'value1';

//also works
var key_one = keys.ONE;
var obj2 = {key_one: 'value1'};
</script>
Solution

  • The limitation of the literal object syntax is that the names has to be literal. As the names can be specified as an identifer as well as a string, it's not possible to use a variable instead.

    This will create an object with a property n, not a property answer:

    var n = 'answer';
var o = { n: 42 };