What's the function of the "
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The | in JavaScript is an integer bitwise OR operator. In that context, it strips off any fractional portion returned by parseFloat . The expression parseFloat($(this).val()) will result in a number with (potentially) a fractional component, but then |0 will convert it to an integer number, OR it with 0 (which means it won't change), and so the overall result is to get a whole number.
So functionally, it truncates the fractional portion off the number. -1.5 becomes -1 , and 1.5 becomes 1 . This is like Math.floor , but truncating rather than rounding "down" ( Math.floor(-1.5) is -2 — the next lowest whole number — rather than -1 as the |0 version gives us).
So perhaps that's why it was used, to chop off (rather than "floor") the fractional portion of the number.
Alternately, it could be a typo. The author of that code might have meant to write this (note || rather than | ):
Total += parseFloat($(this).val()) || 0;
That defends against the possibility that $(this).val() returns "" or similar, resulting in parseFloat returning NaN . It uses the curiously-powerful || operator to return 0 rather than NaN in that case. (And there's an advertisement for putting spaces around your operators.) Would have to know the context of the code to say whether truncating to a whole number ( | ) makes sense when adding to Total , or if they were just defending the NaN case.
The | operator in javascript is the bitwise or operator
This operator treats the operands as 32 bit integers and for every bit returns 1 if either is 1 and 0 otherwise.
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