Re: Math.random().toString(radix).substr(2) 的長度問題

涴跺茼蜆岆toString(r)腔呾楊祥肮﹝勤衾r=10眕俋腔①錶ㄛecma寞毓羶衄寞隅撿极呾楊﹝

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掀��0.5ㄛ媼輛秶憩岆0.1(2)ㄛ侐輛秶憩岆0.2ㄛ16輛秶憩岆0.8﹝

筍岆��輛秶憩岆0.11111111111111111111111111111...

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扂跺�侞蓔藣硨閛轟F腔呾楊載疑珨虳﹝




2011/2/11 Timothy Chien <timdream@gmail.com>

> 爛ヶ��賸珨��最宒ㄛ竭�迠髲閩� webkit 奻醱�y���]婓 Firefox 奻醱�yㄛ
> 磐彆 demo 腔�r緊憩旍嶱賸 orz  ...
>
> 郔摽追政衄��觳腔最宒徨岆�@��ㄩ
> var randomString = Math.random().toString(16).substr(2); // substr(2) 岆參ヶ醱腔
> "0." 鏽裁
>
> 婓 WebkitㄛrandomString 腔墿僅��婓 7 睿 8 眳嶲泐ㄛ
> Firefox �t岆 13 麼岆 14 .......
>
> 摽�簆���賸狟蹈腔最宒徨�� randomString 腔墿僅嘐隅婓 16ㄩ
>
> var randomString = (function () {
>         var num = '';
>         while (num.length < 16) {
>             num += Math.random().toString(16).substr(2);
>         }
>         return num.substr(0,16);
>     })();
>
> 筍岆��岆砑猁捼脤�樨荷N�����g罜ん衄�@�N湮腔船��﹝
> ���r扂睿肮岈腔磐��岆ㄛ
> 螜挲 ECMAScript [1] 衄��隅 Number 倰�e腔�菁窐�  64-bit format IEEE 754 valueㄛ0~1 眳嶲衄
> 2^64 ��硉 [2]ㄛ
> 筍岆 webkit 腔樑�y�筑a汜ん祥��蚚善垀衄腔弇�童��快� toString(16) 眳摽腔墿僅躲 Firefox 祥珨�荂�
> 硐岆扂赻撩珩�]苤陑ㄛ眕�� random() 腔苤�詞c墿僅岆嘐隅腔﹝
>
> 祥綎儸ㄛ摽�簐碻刳銨� toString(radix) [3] 腔 radix (筳弇)ㄛ
> 追政☆Webkit 家汜腔弇�菟L僅珨隅掀廌傻★�@璃岈①祥珨隅岆�朴耀�
> redix = 31 腔��ㄛwebkit 腔墿僅郔墿褫眕善 1024ㄐFirefox 硐��善 11﹝
>
> �M髦�y腔 Orz ��眳�蝜�復隅岆 spec 麼岆 implantation 腔嶒腔��褫眕�馧鶲奴�
> 艘跪弇珂筳衄�]衄朼�N idea﹝
>
> 婬崋�N�衵窒奿��G奻 WTFjs XDDDD
>
>
> Tim
>
> [1] http://www.ecmascript.org/docs.php, 4.3.19, pdf page 5
> [2]
> https://developer.mozilla.org/en/JavaScript/Reference/Global_Objects/Math/random
> [3]
> https://developer.mozilla.org/en/JavaScript/Reference/Global_Objects/Number/toString
>
>