I need to figure out how to create a dynamic key string for an object. This expression makes JavaScript complain.
return {$(this).val(): true}; // returns an object e.g. {2: true}
What am I doing wrong?
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You have to create the object, then use bracket notation for the dynamic key
var obj = {};
var val = $(this).val();
obj[val] = true;
return obj;
or a completely unnecessary one-liner
return (function(o,e) {o[e.value]=true; return o;})({}, this);
adeneo
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1meh. too slow. what adeneo said. – Dbl Apr 14 '14 at 12:18
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@AndreasMüller: ditto :P – Amadan Apr 14 '14 at 12:18
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Anyway to do this in one line? =) – silkfire Apr 14 '14 at 12:19
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1@silkfire: `var obj = {}; var val = $(this).val(); obj[val] = true; return obj;` :P (Serious answer: no) – Amadan Apr 14 '14 at 12:20
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1@silkfire: Not directly in an initializer, no. If you absolutely, positively **must** do it where a single expression is needed, you have to use an inline function: `var obj = (function(val) { var o = {}; o[val] = true; return o;})($(this).val());` Normally, of course, you don't want to do that. – T.J. Crowder Apr 14 '14 at 12:21
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`return (function(o,e) {o[e.value]=true; return o;})({}, this);` – adeneo Apr 14 '14 at 12:21
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Use a function if you want a one-liner. – Florian Margaine Apr 14 '14 at 12:26
1
The JavaScript object literal syntax {x: y} specifies that x will be a (possibly) quoteless string, and y any value. You can't use this syntax for dynamic keys.
Use this instead:
var foo = {};
foo[$(this).val()] = true;
return foo;
Amadan
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