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# FAQ Topic - How do I convert a Number into a String with exactly 2 decimal places? (2008-10-29)

 P: n/a ----------------------------------------------------------------------- FAQ Topic - How do I convert a Number into a String with exactly 2 decimal places? ----------------------------------------------------------------------- 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 -- Postings such as this are automatically sent once a day. Their goal is to answer repeated questions, and to offer the content to the community for continuous evaluation/improvement. The complete comp.lang.javascript FAQ is at http://jibbering.com/faq/index.html. The FAQ workers are a group of volunteers. The sendings of these daily posts are proficiently hosted by http://www.pair.com. Oct 29 '08 #1