blocks|key|961614|text|为什么不直接从Math.random()字符串表示中提取数字呢？|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|961615|Math.random().toString().slice(2,11);
/*
Math.random()+++++++++++++++++++++++++->++0.12345678901234
+++++++++++++.toString()++++++++++++++->+"0.12345678901234"
++++++++++++++++++++++++.slice(2,11)++->+++"123456789"
+*/|code-block|syntax|javascript|961616|(要求每个javascript实现Math.random()的精度至少是9位小数)|961617|entityMap^0|7|D|0|0|H|D|0^^$0|@$1|2|3|4|5|6|7|O|8|@$9|P|A|Q|B|C]]|D|@]|E|$]]|$1|F|3|G|5|H|7|R|8|@]|D|@]|E|$I|J]]|$1|K|3|L|5|6|7|S|8|@$9|T|A|U|B|C]]|D|@]|E|$]]|$1|M|3|-4|5|6|7|V|8|@]|D|@]|E|$]]]|N|$]]

why don't just extract digits from the <code>Math.random()</code> string representation?

<pre><code>Math.random().toString().slice(2,11);
/*
Math.random() -&gt; 0.12345678901234
 .toString() -&gt; "0.12345678901234"
 .slice(2,11) -&gt; "123456789"
 */
</code></pre>

(requirement is that every javascript implementation <code>Math.random()</code>'s precision is at least 9 decimal places)

blocks|key|1175946|text|还有..。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1175947|function+getRandom(length)+{

return+Math.floor(Math.pow(10,+length-1)+%2B+Math.random()+*+9+*+Math.pow(10,+length-1));

}|code-block|syntax|javascript|1175948|getRandom(9)+=>+234664534|1175949|entityMap^0|0|0|0^^$0|@$1|2|3|4|5|6|7|K|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|L|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|M|8|@]|9|@]|A|$]]|$1|I|3|-4|5|6|7|N|8|@]|9|@]|A|$]]]|J|$]]

Also...

<pre><code>function getRandom(length) {

return Math.floor(Math.pow(10, length-1) + Math.random() * 9 * Math.pow(10, length-1));

}
</code></pre>

getRandom(9) => 234664534

blocks|key|961696|text|我找到了三种方法，按效率排序：(测试运行Firefox+7.0+Win+XP的机器)|type|unstyled|depth|inlineStyleRanges|entityRanges|data|961697|parseInt(Math.random()*1000000000,+10)|code-block|syntax|javascript|961698|100万次迭代：~626ms。到目前为止最快的-+parseInt是一个本机函数，而不是再次调用数学库。注:见下文。|961699|Math.floor(Math.random()*1000000000)|961700|100万次迭代：~1005ms。两个函数调用。|961701|String(Math.random()).substring(2,11)|961702|100万次迭代:约2997ms。三个函数调用。|961703|还有..。|961704|parseInt(Math.random()*1000000000)|961705|100万次迭代:约362ms。注意:+parseInt通常被认为在没有基数参数的情况下使用是不安全的。请参阅https://developer.mozilla.org/en/JavaScript/Reference/Global_Objects/parseInt或谷歌的"JavaScript:好的部分“。但是，传递给parseInt的参数似乎永远不会以'0‘或'0x’开头，因为输入是先乘以1000000000。YMMV.|offset|length|961706|entityMap|0|LINK|mutability|MUTABLE|url|https://developer.mozilla.org/en/JavaScript/Reference/Global_Objects/parseInt^0|0|0|0|0|0|0|0|0|0|1I|25|0|0^^$0|@$1|2|3|4|5|6|7|16|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|17|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|18|8|@]|9|@]|A|$]]|$1|I|3|J|5|D|7|19|8|@]|9|@]|A|$E|F]]|$1|K|3|L|5|6|7|1A|8|@]|9|@]|A|$]]|$1|M|3|N|5|D|7|1B|8|@]|9|@]|A|$E|F]]|$1|O|3|P|5|6|7|1C|8|@]|9|@]|A|$]]|$1|Q|3|R|5|6|7|1D|8|@]|9|@]|A|$]]|$1|S|3|T|5|D|7|1E|8|@]|9|@]|A|$E|F]]|$1|U|3|V|5|6|7|1F|8|@]|9|@$W|1G|X|1H|1|1I]]|A|$]]|$1|Y|3|-4|5|6|7|1J|8|@]|9|@]|A|$]]]|Z|$10|$5|11|12|13|A|$14|15]]]]

Three methods I've found in order of efficiency:
(Test machine running Firefox 7.0 Win XP)

<pre><code>parseInt(Math.random()*1000000000, 10)
</code></pre>

1 million iterations: ~626ms. By far the fastest - parseInt is a native function vs calling the Math library again. NOTE: See below.

<pre><code>Math.floor(Math.random()*1000000000)
</code></pre>

1 million iterations: ~1005ms. Two function calls.

<pre><code>String(Math.random()).substring(2,11)
</code></pre>

1 million iterations: ~2997ms. Three function calls.

And also...

<pre><code>parseInt(Math.random()*1000000000)
</code></pre>

1 million iterations: ~362ms. 
NOTE: parseInt is usually noted as unsafe to use without radix parameter. See <a href="https://developer.mozilla.org/en/JavaScript/Reference/Global_Objects/parseInt">https://developer.mozilla.org/en/JavaScript/Reference/Global_Objects/parseInt</a> or google "JavaScript: The Good Parts". However, it seems the parameter passed to parseInt will never begin with '0' or '0x' since the input is first multiplied by 1000000000. YMMV.

blocks|key|1176112|text|Math.random().toFixed(length).split('.')[1]|type|code-block|depth|inlineStyleRanges|entityRanges|data|syntax|javascript|1176113|使用toFixed允许您设置比默认长度更长的长度(似乎在小数点后生成15-16位。如果你需要的话，ToFixed会让你得到更多的数字。|unstyled|1176114|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$B|C]]|$1|D|3|E|5|F|7|J|8|@]|9|@]|A|$]]|$1|G|3|-4|5|F|7|K|8|@]|9|@]|A|$]]]|H|$]]

<pre><code>Math.random().toFixed(length).split('.')[1]
</code></pre>

Using toFixed alows you to set the length longer than the default (seems to generate 15-16 digits after the decimal. ToFixed will let you get more digits if you need them.

blocks|key|1176052|text|我想我会尝试一下你的问题。当我运行以下代码时，它对我起作用了。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1176053|<script+type="text/javascript">

++++function+getRandomInt(min,+max)+{
++++return+Math.floor(Math.random()+*+(max+-+min))+%2B+min;
++++}+//The+maximum+is+exclusive+and+the+minimum+is+inclusive
++++$(document).ready(function()+{

++++$("#random-button").on("click",+function()+{
++++var+randomNumber+=+getRandomInt(100000000,+999999999);
++++$("#random-number").html(randomNumber);
++++});

</script>|code-block|syntax|javascript|1176054|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

Thought I would take a stab at your question. When I ran the following code it worked for me. 

<pre><code>&lt;script type="text/javascript"&gt;

 function getRandomInt(min, max) {
 return Math.floor(Math.random() * (max - min)) + min;
 } //The maximum is exclusive and the minimum is inclusive
 $(document).ready(function() {

 $("#random-button").on("click", function() {
 var randomNumber = getRandomInt(100000000, 999999999);
 $("#random-number").html(randomNumber);
 });

&lt;/script&gt;
</code></pre>

blocks|key|961870|text|function+rand(len){var+x='';
+for(var+i=0;i<len;i%2B%2B){x%2B=Math.floor(Math.random()+*+10);}
+return+x;
}

rand(9);|type|code-block|depth|inlineStyleRanges|entityRanges|data|syntax|javascript|961871|unstyled|entityMap^0|0^^$0|@$1|2|3|4|5|6|7|G|8|@]|9|@]|A|$B|C]]|$1|D|3|-4|5|E|7|H|8|@]|9|@]|A|$]]]|F|$]]

<pre><code>function rand(len){var x='';
 for(var i=0;i&lt;len;i++){x+=Math.floor(Math.random() * 10);}
 return x;
}

rand(9);
</code></pre>

blocks|key|1176180|text|这个问题已经有足够的答案了吗？|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1176181|我想不是。因此，即使Math.random()决定返回像0.000235436这样的内容，它也应该可靠地提供一个9位数|offset|length|style|CODE|1176182|Math.floor((Math.random()+%2B+Math.floor(Math.random()*9)%2B1)+*+Math.pow(10,+8))|code-block|syntax|javascript|1176183|entityMap^0|0|A|D|S|B|0|0^^$0|@$1|2|3|4|5|6|7|O|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|P|8|@$D|Q|E|R|F|G]|$D|S|E|T|F|G]]|9|@]|A|$]]|$1|H|3|I|5|J|7|U|8|@]|9|@]|A|$K|L]]|$1|M|3|-4|5|6|7|V|8|@]|9|@]|A|$]]]|N|$]]

Does this already have enough answers? 
I guess not. So, this should reliably provide a number with 9 digits, even if <code>Math.random()</code> decides to return something like <code>0.000235436</code>:

<pre><code>Math.floor((Math.random() + Math.floor(Math.random()*9)+1) * Math.pow(10, 8))
</code></pre>

blocks|key|961553|text|Math.floor(Math.random()*899999999+%2B+100000000)；|type|unstyled|depth|inlineStyleRanges|entityRanges|data|961554|entityMap^0|0^^$0|@$1|2|3|4|5|6|7|D|8|@]|9|@]|A|$]]|$1|B|3|-4|5|6|7|E|8|@]|9|@]|A|$]]]|C|$]]

Math.floor(Math.random()*899999999 + 100000000);

blocks|key|1176011|text|如果你想生成随机的电话号码，那么他们通常被禁止从零开始。这就是为什么你应该组合几个方法：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1176012|Math.floor(Math.random()*8%2B1)%2BMath.random().toString().slice(2,10);|code-block|syntax|javascript|1176013|这将生成100+000+000到999+999+999之间的随机数|1176014|对于其他方法，我在获得可靠的结果时遇到了一些麻烦，因为前导零不知何故是一个问题。|1176015|entityMap^0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|M|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|N|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|O|8|@]|9|@]|A|$]]|$1|I|3|J|5|6|7|P|8|@]|9|@]|A|$]]|$1|K|3|-4|5|6|7|Q|8|@]|9|@]|A|$]]]|L|$]]

If you mean to generate random telephone number, then they usually are forbidden to start with zero. 
That is why you should combine few methods: 

<pre><code>Math.floor(Math.random()*8+1)+Math.random().toString().slice(2,10);
</code></pre>

this will generate random in between 100 000 000 to 999 999 999

With other methods I had a little trouble to get reliable results as leading zeroes was somehow a problem.

blocks|key|961924|text|function+randomCod(){

++++let+code+=+"";
++++let+chars+=+'abcdefghijlmnopqrstuvxwz';+
++++let+numbers+=+'0123456789';
++++let+specialCaracter+=+'/{}$%25&@*/()!-=?<>';
++++for(let+i+=+4;+i+>+1;+i--){

++++++++let+random+=+Math.floor(Math.random()+*+99999).toString();
++++++++code+%2B=+specialCaracter[random.substring(i,+i-1)]+%2B+((parseInt(random.substring(i,+i-1))+%25+2+==+0)+?+(chars[random.substring(i,+i-1)].toUpperCase())+:+(chars[random.substring(i,+i%2B1)]))+%2B+(numbers[random.substring(i,+i-1)]);
++++}

++++code+=+(code.indexOf("undefined")+>+-1+%7C%7C+code.indexOf("NaN")+>+-1)+?+randomCod()+:+code;


++++return+code;
}|type|code-block|depth|inlineStyleRanges|entityRanges|data|syntax|javascript|961925|unstyled|entityMap^0|0^^$0|@$1|2|3|4|5|6|7|G|8|@]|9|@]|A|$B|C]]|$1|D|3|-4|5|E|7|H|8|@]|9|@]|A|$]]]|F|$]]

<pre><code>function randomCod(){

 let code = "";
 let chars = 'abcdefghijlmnopqrstuvxwz'; 
 let numbers = '0123456789';
 let specialCaracter = '/{}$%&amp;@*/()!-=?&lt;&gt;';
 for(let i = 4; i &gt; 1; i--){

 let random = Math.floor(Math.random() * 99999).toString();
 code += specialCaracter[random.substring(i, i-1)] + ((parseInt(random.substring(i, i-1)) % 2 == 0) ? (chars[random.substring(i, i-1)].toUpperCase()) : (chars[random.substring(i, i+1)])) + (numbers[random.substring(i, i-1)]);
 }

 code = (code.indexOf("undefined") &gt; -1 || code.indexOf("NaN") &gt; -1) ? randomCod() : code;


 return code;
}
</code></pre>

blocks|key|1176246|text|为了生成长度为n的数字字符串，多亏了@nvitaterna，我想出了这个：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1176247|1+%2B+Math.floor(Math.random()+*+9)+%2B+Math.random().toFixed(n+-+1).split('.')[1]|code-block|syntax|javascript|1176248|它可以防止第一个数字为零。每次调用它都会生成长度约为50的字符串。|1176249|entityMap^0|0|0|0^^$0|@$1|2|3|4|5|6|7|K|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|L|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|M|8|@]|9|@]|A|$]]|$1|I|3|-4|5|6|7|N|8|@]|9|@]|A|$]]]|J|$]]

To generate a number string with length n, thanks to @nvitaterna, I came up with this:
<pre><code>1 + Math.floor(Math.random() * 9) + Math.random().toFixed(n - 1).split('.')[1]
</code></pre>
It prevents first digit to be zero.
It can generate string with length ~ 50 each time you call it.

I'm looking for an efficient, elegant way to generate a JavaScript variable that is 9 digits in length:

Example: 323760488

JavaScript, Generate a Random Number that is 9 numbers in length

我正在寻找一种高效、优雅的方法来生成长度为9位数的JavaScript变量：示例: 323760488

问JavaScript，生成一个长度为9个数字的随机数
EN

回答 11

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问JavaScript，生成一个长度为9个数字的随机数EN

回答 11

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问JavaScript，生成一个长度为9个数字的随机数
EN