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FAQ Topic - Why does 1+1 equal 11? or How do I convert a
string to a number?
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Javascript variables are loosely typed: the conversion between a
string and a number happens automatically. Since plus (+) is also
used as in string concatenation, ` '1' + 1 ` is equal to ` '11' `: the
String deciding what + does. To overcome this, first convert the
string to a number. For example: ` +varname ` or ` Number(varname) ` or
` parseInt(varname, 10) ` or ` parseFloat(varname) `.
Prompt and form control values are strings, as is the result from
a prompt window. Convert these to numbers before performing addition.

Additional Notes:

http://www.jibbering.com/faq/faq_not...e_convert.html

http://msdn2.microsoft.com/en-us/library/67defydd.aspx


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