Javascript - Error while concatnating objects

Question

While executing the below snippet, I'm getting an error stating "Uncaught TypeError: undefined is not a function" error.

Can someone shed some light here?.

var a1={'Param1':'122','Param2':'123','Param3':'124','Param4':'125'};
var b={'Param1':'22','Param2':'23','Param3':'24','Param4':'25'};
var c=a1.concat(b);

Thanks, Dave

`concat` is defined for Array and String objects in Javascript. JSON doesn't have this defined :) — MIdhun Krishna, Jul 21 '14 at 06:10
@MattHarrison I meant `JavaScript Object Literal` or Javascript Object. :) I cant edit my previous comment, else would have corrected it. — MIdhun Krishna, Jul 21 '14 at 06:39
@MIdhunKrishna hehe, no worries. Just feeling pedantic this morning ;) — Matt Harrison, Jul 21 '14 at 06:41

score 0 · Answer 1 · answered Jul 21 '14 at 06:09

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Object.prototype.concat is undefined. concat is a method on an array or string.

instead use:

for (var attrname in b) { a1[attrname] = b[attrname]; }

answered Jul 21 '14 at 06:09

Matt Harrison

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score 0 · Accepted Answer · answered Jul 21 '14 at 06:09

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a1 is an object and javascript object does not have a concat method.

Concat is available for strings and arrays

answered Jul 21 '14 at 06:09

Lucky Soni

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Thanks Soni! Thanks for answering! – David R Jul 21 '14 at 06:24

Javascript - Error while concatnating objects

2 Answers2