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FAQ Topic - How do I format a Number as a String with

exactly 2 decimal places?

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When formatting money for example, to format 6.57634 to

6.58, 6.5 to 6.50, and 6 to 6.00?

Rounding of x.xx5 is uncertain, as such numbers are not

represented exactly. See the section on "simple decimal arithmetic"

for Rounding issues.

` N = Math.round(N*100)/100 ` only converts N to a Number of value

close to a multiple of 0.01; but ` document.write(N) ` does not give

trailing zeroes.

ECMAScript Ed. 3.0 (JScript 5.5 [but buggy] and JavaScript 1.5)

introduced ` Number.prototype.toFixed `, the main problem

with this is the bugs in JScript's implementation.

Most implementations fail with certain numbers, for example 0.07.

The following works successfully for ` M>0, N>0: `

function Stretch(Q, L, c) { var S = Q

if (c.length 0) {

while (S.length < L) {

S = c+S;

}

}

return S;

}

function StrU(X, M, N) { // X>=0.0

var T, S = String(Math.round(X * Number("1e" + N)));

if (S.search && S.search(/\D/) != -1) {

return '' + X;

}

with (String(Stretch(S, M+N, '0')))

return substring(0, T = (length-N)) + '.' + substring(T);

}

function Sign(X) {

return X 0 ? "+" : X < 0 ? "-" : " ";

}

function StrS(X, M, N) {

return Sign(X) + StrU(Math.abs(X), M, N);

}

Number.prototype.toFixed = function(n){

return StrS(this, 1, n);

};

http://www.merlyn.demon.co.uk/js-round.htm http://msdn2.microsoft.com/en-us/library/sstyff0z.aspx
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