blocks|key|1873229|text|您可以直接比较Math.random()和0.5，因为Math.random()的范围是[0,+1)+(这意味着‘在0到1的范围内，包括0，但不是1')。您可以将范围分为[0,+0.5)和[0.5,+1)。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|1873230|var+random_boolean+=+Math.random()+<+0.5;|code-block|syntax|javascript|1873231|​|1873232|//+Example
console.log(Math.random()+<+0.1);+//10%25+probability+of+getting+true
console.log(Math.random()+<+0.4);+//40%25+probability+of+getting+true
console.log(Math.random()+<+0.5);+//50%25+probability+of+getting+true
console.log(Math.random()+<+0.8);+//80%25+probability+of+getting+true
console.log(Math.random()+<+0.9);+//90%25+probability+of+getting+true|1873233|1873234|entityMap^0|7|D|L|3|R|D|18|6|2D|8|2M|8|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|R|8|@$9|S|A|T|B|C]|$9|U|A|V|B|C]|$9|W|A|X|B|C]|$9|Y|A|Z|B|C]|$9|10|A|11|B|C]|$9|12|A|13|B|C]]|D|@]|E|$]]|$1|F|3|G|5|H|7|14|8|@]|D|@]|E|$I|J]]|$1|K|3|L|5|6|7|15|8|@]|D|@]|E|$]]|$1|M|3|N|5|H|7|16|8|@]|D|@]|E|$I|J]]|$1|O|3|L|5|6|7|17|8|@]|D|@]|E|$]]|$1|P|3|-4|5|6|7|18|8|@]|D|@]|E|$]]]|Q|$]]

<p>You can compare <code>Math.random()</code> to <code>0.5</code> directly, as the range of <code>Math.random()</code> is <code>[0, 1)</code> (this means 'in the range 0 to 1 including 0, but not 1'). You can divide the range into <code>[0, 0.5)</code> and <code>[0.5, 1)</code>.</p>
<pre><code>var random_boolean = Math.random() &lt; 0.5;
</code></pre>
<p><div class="snippet" data-lang="js" data-hide="false" data-console="true" data-babel="false">
<div class="snippet-code">
<pre class="snippet-code-js lang-js prettyprint-override"><code>// Example
console.log(Math.random() &lt; 0.1); //10% probability of getting true
console.log(Math.random() &lt; 0.4); //40% probability of getting true
console.log(Math.random() &lt; 0.5); //50% probability of getting true
console.log(Math.random() &lt; 0.8); //80% probability of getting true
console.log(Math.random() &lt; 0.9); //90% probability of getting true</code></pre>
</div>
</div>
</p>


blocks|key|2087162|text|为了获得更安全的密码学上的值，您可以在现代浏览器中使用crypto.getRandomValues。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|2087163|示例：|2087164|​|2087165|var+randomBool+=+(function()+{
++var+a+=+new+Uint8Array(1);
++return+function()+{
++++crypto.getRandomValues(a);
++++return+a[0]+>+127;
++};
})();

var+trues+=+0;
var+falses+=+0;
for+(var+i+=+0;+i+<+255;+i%2B%2B)+{
++if+(randomBool())+{
++++trues%2B%2B;
++}
++else+{
++++falses%2B%2B;
++}
}
document.body.innerText+=+'true:+'+%2B+trues+%2B+',+false:+'+%2B+falses;|code-block|syntax|javascript|2087166|2087167|请注意，crypto对象是DOM，因此它在Node中不可用，而在there+is+a+similar+API+for+Node中可用。|2087168|entityMap|0|LINK|mutability|MUTABLE|url|https://developer.mozilla.org/en-US/docs/Web/API/RandomSource/getRandomValues|1|https://stackoverflow.com/questions/25725596/use-window-crypto-in-nodejs-code^0|R|M|R|M|0|0|0|0|0|0|4|6|W|V|1|0^^$0|@$1|2|3|4|5|6|7|11|8|@$9|12|A|13|B|C]]|D|@$9|14|A|15|1|16]]|E|$]]|$1|F|3|G|5|6|7|17|8|@]|D|@]|E|$]]|$1|H|3|I|5|6|7|18|8|@]|D|@]|E|$]]|$1|J|3|K|5|L|7|19|8|@]|D|@]|E|$M|N]]|$1|O|3|I|5|6|7|1A|8|@]|D|@]|E|$]]|$1|P|3|Q|5|6|7|1B|8|@$9|1C|A|1D|B|C]]|D|@$9|1E|A|1F|1|1G]]|E|$]]|$1|R|3|-4|5|6|7|1H|8|@]|D|@]|E|$]]]|S|$T|$5|U|V|W|E|$X|Y]]|Z|$5|U|V|W|E|$X|10]]]]

<p>For a more cryptographically secure value, you can use <a href="https://developer.mozilla.org/en-US/docs/Web/API/RandomSource/getRandomValues" rel="noreferrer"><code>crypto.getRandomValues</code></a> in modern browsers.</p>

<h3>Sample:</h3>

<p><div class="snippet" data-lang="js" data-hide="false" data-console="false" data-babel="false">
<div class="snippet-code">
<pre class="snippet-code-js lang-js prettyprint-override"><code>var randomBool = (function() {
  var a = new Uint8Array(1);
  return function() {
    crypto.getRandomValues(a);
    return a[0] &gt; 127;
  };
})();

var trues = 0;
var falses = 0;
for (var i = 0; i &lt; 255; i++) {
  if (randomBool()) {
    trues++;
  }
  else {
    falses++;
  }
}
document.body.innerText = 'true: ' + trues + ', false: ' + falses;</code></pre>
</div>
</div>
</p>

<p>Note that the <code>crypto</code> object is a DOM API, so it's not available in Node, but <a href="https://stackoverflow.com/questions/25725596/use-window-crypto-in-nodejs-code">there is a similar API for Node</a>.</p>


blocks|key|1873255|text|如果你的项目有lodash，那么你可以：|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|1873256|_.sample([true,+false])|code-block|syntax|javascript|1873257|或者，您可以使用自己的示例函数(source)：|1873258|const+sample+=+arr+=>+arr[Math.floor(Math.random()+*+arr.length)];|1873259|entityMap|0|LINK|mutability|MUTABLE|url|https://lodash.com/|1|https://www.30secondsofcode.org/js/s/sample^0|7|6|7|6|0|0|0|G|6|1|0|0^^$0|@$1|2|3|4|5|6|7|Y|8|@$9|Z|A|10|B|C]]|D|@$9|11|A|12|1|13]]|E|$]]|$1|F|3|G|5|H|7|14|8|@]|D|@]|E|$I|J]]|$1|K|3|L|5|6|7|15|8|@]|D|@$9|16|A|17|1|18]]|E|$]]|$1|M|3|N|5|H|7|19|8|@]|D|@]|E|$I|J]]|$1|O|3|-4|5|6|7|1A|8|@]|D|@]|E|$]]]|P|$Q|$5|R|S|T|E|$U|V]]|W|$5|R|S|T|E|$U|X]]]]

<p>If your project has <a href="https://lodash.com/" rel="noreferrer"><code>lodash</code></a> then you can:</p>
<pre><code>_.sample([true, false])
</code></pre>
<p>Alternatively you can use your own sample function (<a href="https://www.30secondsofcode.org/js/s/sample" rel="noreferrer">source</a>):</p>
<pre><code>const sample = arr =&gt; arr[Math.floor(Math.random() * arr.length)];
</code></pre>


blocks|key|2087213|text|这个怎么样？|type|unstyled|depth|inlineStyleRanges|entityRanges|data|2087214|return+Math.round((Math.random()+*+1)+%2B+0)+===+0;|code-block|syntax|javascript|2087215|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|$]]

<p>How about this one?</p>

<pre><code>return Math.round((Math.random() * 1) + 0) === 0;
</code></pre>


blocks|key|1873264|text|!Math.round(Math.random());|type|code-block|depth|inlineStyleRanges|entityRanges|data|syntax|javascript|1873265|…|unstyled|1873266|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.round(Math.random());
</code></pre>

<p>­­­­­­­­­­­­­­</p>


blocks|key|2087229|text|Kelvin's+answer给我留下了很深的印象，我想建议一个相当类似但略有增强的解决方案。|type|unstyled|depth|inlineStyleRanges|entityRanges|offset|length|data|2087230|var+randomBoolean+=+Math.random()+<+0.5;|code-block|syntax|javascript|2087231|这个解决方案更容易理解，因为<右侧的数字告诉您获得true的概率，而不是获得false的概率，这更容易理解。此外，<比>=短一个符号；|style|CODE|2087232|entityMap|0|LINK|mutability|MUTABLE|url|https://stackoverflow.com/a/36756480/7212563^0|0|F|0|0|0|E|1|P|4|12|5|1L|1|1N|2|0^^$0|@$1|2|3|4|5|6|7|U|8|@]|9|@$A|V|B|W|1|X]]|C|$]]|$1|D|3|E|5|F|7|Y|8|@]|9|@]|C|$G|H]]|$1|I|3|J|5|6|7|Z|8|@$A|10|B|11|K|L]|$A|12|B|13|K|L]|$A|14|B|15|K|L]|$A|16|B|17|K|L]|$A|18|B|19|K|L]]|9|@]|C|$]]|$1|M|3|-4|5|6|7|1A|8|@]|9|@]|C|$]]]|N|$O|$5|P|Q|R|C|$S|T]]]]

<p>Impressed a lot by <a href="https://stackoverflow.com/a/36756480/7212563">Kelvin's answer</a> I would like to suggest a fairly similar but slightly enhanced solution.</p>

<pre><code>var randomBoolean = Math.random() &lt; 0.5;
</code></pre>

<p>This solution is a bit more obvious to read, because the number on the right-hand side of <code>&lt;</code> tells you the probability of getting <code>true</code> rather than of getting <code>false</code>, which is more natural to comprehend. Also <code>&lt;</code> is one symbol shorter than <code>&gt;=</code>;</p>


blocks|key|2087352|text|潜在的更快的解决方案...|type|unstyled|depth|inlineStyleRanges|entityRanges|data|2087353|按位运算符方法我只想到了Math.random()+%2B+.5+>>+0或~~(Math.random()+%2B+.5)。这里有一个你可以自己判断的performance+test。|offset|length|style|CODE|2087354|let+randomBoolean+=+Math.random()+%2B+.5+>>+0;+++++++++++++++++//chance+of+true
const+randomBoolean+=+chance+=>+Math.random()+%2B+chance+>>+0;+//chance+of+true|code-block|syntax|javascript|2087355|在这种情况下，按位运算符基本上与使用Math.trunc()或Math.floor()相同，因此这也是可能的Math.trunc(Math.random()+%2B+.5)。|2087356|let+randomBoolean+=+Math.trunc(Math.random()+%2B+.5);
const+randomBoolean+=+chance+=>+Math.trunc(Math.random()+%2B+chance);|2087357|其他更常见的解决方案|2087358|更常见的获取随机布尔值的方法可能是比较方法，比如Kelvin's+answer的Math.random()+>=+.5或Arthur+Khazbs's+answer的Math.random()+<+.5;，它们实际上输出true+&+false，而不是1&+0。|2087359|let+randomBoolean+=+Math.random()+>=+.5;+++++++++++++++++//chance+of+false
const+randomBoolean+=+chance+=>+Math.random()+>=+chance;+//chance+of+false

let+randomBoolean+=+Math.random()++<+.5;+++++++++++++++++//chance+of+true
const+randomBoolean+=+chance+=>+Math.random()+<+chance;++//chance+of+true|2087360|使用Math.round(Math.random())方法的唯一原因是简单和懒惰。|2087361|entityMap|0|LINK|mutability|MUTABLE|url|https://jsben.ch/1BDOG|1|https://stackoverflow.com/a/36756480/10456329|2|https://stackoverflow.com/a/60322877/10456329^0|0|C|N|10|M|20|G|0|0|0|I|C|V|C|1I|U|0|0|0|14|J|2B|J|O|F|1|1O|M|2|0|0|2|P|0^^$0|@$1|2|3|4|5|6|7|1A|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|1B|8|@$D|1C|E|1D|F|G]|$D|1E|E|1F|F|G]]|9|@$D|1G|E|1H|1|1I]]|A|$]]|$1|H|3|I|5|J|7|1J|8|@]|9|@]|A|$K|L]]|$1|M|3|N|5|6|7|1K|8|@$D|1L|E|1M|F|G]|$D|1N|E|1O|F|G]|$D|1P|E|1Q|F|G]]|9|@]|A|$]]|$1|O|3|P|5|J|7|1R|8|@]|9|@]|A|$K|L]]|$1|Q|3|R|5|6|7|1S|8|@]|9|@]|A|$]]|$1|S|3|T|5|6|7|1T|8|@$D|1U|E|1V|F|G]|$D|1W|E|1X|F|G]]|9|@$D|1Y|E|1Z|1|20]|$D|21|E|22|1|23]]|A|$]]|$1|U|3|V|5|J|7|24|8|@]|9|@]|A|$K|L]]|$1|W|3|X|5|6|7|25|8|@$D|26|E|27|F|G]]|9|@]|A|$]]|$1|Y|3|-4|5|6|7|28|8|@]|9|@]|A|$]]]|Z|$10|$5|11|12|13|A|$14|15]]|16|$5|11|12|13|A|$14|17]]|18|$5|11|12|13|A|$14|19]]]]

<h1>Potentialy faster solutions...</h1>
<p>Bitwise operator approach i just thought of <code>Math.random() + .5 &gt;&gt; 0</code> or <code>~~(Math.random() + .5)</code>. Here is a <a href="https://jsben.ch/1BDOG" rel="nofollow noreferrer">performance test</a> to judge for yourself.</p>
<pre><code>let randomBoolean = Math.random() + .5 &gt;&gt; 0;                 //chance of true
const randomBoolean = chance =&gt; Math.random() + chance &gt;&gt; 0; //chance of true
</code></pre>
<p>The bitwise operators is in this case essentially just the same as using <code>Math.trunc()</code> or <code>Math.floor()</code>, therefore this is also posible <code>Math.trunc(Math.random() + .5)</code>.</p>
<pre><code>let randomBoolean = Math.trunc(Math.random() + .5);
const randomBoolean = chance =&gt; Math.trunc(Math.random() + chance);
</code></pre>
<h2>Other more common solutions</h2>
<p>The more common way to get random boolean is probably a comparative approach like  <code>Math.random() &gt;= .5</code> from <a href="https://stackoverflow.com/a/36756480/10456329">Kelvin's answer</a> or <code>Math.random() &lt; .5;</code> from <a href="https://stackoverflow.com/a/60322877/10456329">Arthur Khazbs's answer</a>, they actualy output true &amp; false, and not 1 &amp; 0.</p>
<pre><code>let randomBoolean = Math.random() &gt;= .5;                 //chance of false
const randomBoolean = chance =&gt; Math.random() &gt;= chance; //chance of false

let randomBoolean = Math.random()  &lt; .5;                 //chance of true
const randomBoolean = chance =&gt; Math.random() &lt; chance;  //chance of true
</code></pre>
<p>The only reason to use the <code>Math.round(Math.random())</code> approach is simplicity and laziness.</p>


<p>Simple question, but I'm interested in the nuances here.</p>

<p>I'm generating random booleans using the following method I came up with myself:</p>

<pre><code>const rand = Boolean(Math.round(Math.random()));
</code></pre>

<p>Whenever <code>random()</code> shows up, it seems there's always a pitfall - it's not truly random, it's compromised by something or other, etc.  So, I'd like to know:</p>

<p>a) Is the above the best-practice way to do it? </p>

<p>b) Am I overthinking things? </p>

<p>c) Am I underthinking things?  </p>

<p>d) Is there a better/faster/elegant-er way I don't know of?</p>

<p>(Also somewhat interested if B and C are mutually exclusive.)</p>

<p><em>Update</em></p>

<p>If it makes a difference, I'm using this for movement of an AI character.</p>


JS generate random boolean

问题很简单，但我对这里的细微差别很感兴趣。我使用自己想出的以下方法生成随机布尔值：const rand = Boolean(Math.round(Math.random()));每当random()出现的时候，似乎总是有一个陷阱-它不是真正的随机的，它被一些或其他的东西所折衷，等等。所以，我想知道：a)以上是最佳实践方...

问JS生成随机布尔值
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