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

Discussion in 'Javascript' started by FAQ server, Oct 10, 2008.

  1. FAQ server

    FAQ server Guest

    -----------------------------------------------------------------------
    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.
    FAQ server, Oct 10, 2008
    #1
    1. Advertising

Want to reply to this thread or ask your own question?

It takes just 2 minutes to sign up (and it's free!). Just click the sign up button to choose a username and then you can ask your own questions on the forum.

Share This Page