Javascript Number Formatting

Question

Certainly a stupid question, please forgive me. My customer wants decimal numbers to display with five digits. For example: 100.34 or 37.459. I was accomplishing this with val.toPrecision (5);; however, when my numbers get really small, I stop getting what I want. For example, if my number is 0.000347, it displays 0.00034700. Now, I understand why it's doing this, but what I don't know is how to get it to display 0.0003. Any thoughts?

Check out http://stackoverflow.com/questions/610406/javascript-printf-string-format and the first answer's sprintf link — mrk, Jul 08 '11 at 15:14

katspaugh · Answer 1 · 2011-07-08T17:18:13.030

5

Math.round(0.000347 * 1e4) / 1e4

Or with toFixed:

Number.prototype.toNDigits = function (n) {
    return (Math.abs(this) < 1) ?
        this.toFixed(n - 1) :
        this.toPrecision(n);
};

http://jsfiddle.net/HeQtH/6/

edited Jul 08 '11 at 17:18

answered Jul 08 '11 at 15:15

katspaugh

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score 2 · Accepted Answer · answered Jul 08 '11 at 15:48

2

Our problem is with numbers less than 1 obviously. So catch them and deal them separately

function SetPrecisionToFive(n){  
    return (n > 1) ? n.toPrecision (5) : (Math.round(n * 1e4) / 1e4).toString();
}

answered Jul 08 '11 at 15:48

naveen

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score 1 · Answer 3 · edited Jul 08 '11 at 17:20

1

You can use the toFixed method to accomplish this. For example: (0.000347).toFixed(4)

edited Jul 08 '11 at 17:20

answered Jul 08 '11 at 15:14

kfegen

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Will toFixed change 100.34298 to 100.34 as he wants? – Michael Myers Jul 08 '11 at 15:15
1

jQuery for `toFixed`, are you kidding? – katspaugh Jul 08 '11 at 15:16
Why would you need to be using jQuery to use `toFixed`? – James Allardice Jul 08 '11 at 15:17
oh pal. just leave jquery once in a while :) – naveen Jul 08 '11 at 15:20
1

You should totally drop that and use jQuery. – Nathan Jul 08 '11 at 17:09

score -1 · Answer 4 · answered Jul 08 '11 at 15:16

-1

The Javascript toFixed() function will truncate small numbers to a fixed decimal precision, eg:

var num = .0000350;
var result = num.toFixed(5); // result will equal .00003

answered Jul 08 '11 at 15:16

Kyle

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Now do `(100.34).toFixed(5)`. – katspaugh Jul 08 '11 at 15:18
@katspaugh this code snippet would be conditional... not meant to cover all cases – Kyle Jul 08 '11 at 15:19

Javascript Number Formatting

4 Answers4