blocks|key|3113528|text|这是一个常见的Javascript陷阱，有一个简单的解决方案：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|3113529|只需specify+the+base，或‘基’，如下所示：|offset|length|3113530|parseInt('08',10);+//+8|code-block|syntax|javascript|3113531|您还可以使用Number|3113532|Number('08');+//+8|3113533|entityMap|0|LINK|mutability|MUTABLE|url|https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/parseInt|1|https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Number^0|0|2|G|0|0|0|6|6|1|0|0^^$0|@$1|2|3|4|5|6|7|Y|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|Z|8|@]|9|@$D|10|E|11|1|12]]|A|$]]|$1|F|3|G|5|H|7|13|8|@]|9|@]|A|$I|J]]|$1|K|3|L|5|6|7|14|8|@]|9|@$D|15|E|16|1|17]]|A|$]]|$1|M|3|N|5|H|7|18|8|@]|9|@]|A|$I|J]]|$1|O|3|-4|5|6|7|19|8|@]|9|@]|A|$]]]|P|$Q|$5|R|S|T|A|$U|V]]|W|$5|R|S|T|A|$U|X]]]]

This is a common Javascript gotcha with a simple solution:

Just <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/parseInt" rel="noreferrer">specify the base</a>, or 'radix', like so:

<pre><code>parseInt('08',10); // 8
</code></pre>

You could also use <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Number" rel="noreferrer">Number</a>:

<pre><code>Number('08'); // 8
</code></pre>

blocks|key|341982|text|如果您知道的值将在有符号的32位整数范围内，那么~~x将在所有情况下执行正确的操作。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|341983|~~"08"+===+8
~~"foobar"+===+0
~~(1.99)+===+1
~~(-1.99)++===+-1|code-block|syntax|javascript|341984|如果查找二进制not+(~)，则规范要求参数进行"ToInt32“转换，该参数执行到Int32的明显转换，并指定强制NaN值为零。|341985|是的，这是令人难以置信的黑客行为，但非常方便……|341986|entityMap^0|O|3|0|0|C|1|1M|3|0|0^^$0|@$1|2|3|4|5|6|7|Q|8|@$9|R|A|S|B|C]]|D|@]|E|$]]|$1|F|3|G|5|H|7|T|8|@]|D|@]|E|$I|J]]|$1|K|3|L|5|6|7|U|8|@$9|V|A|W|B|C]|$9|X|A|Y|B|C]]|D|@]|E|$]]|$1|M|3|N|5|6|7|Z|8|@]|D|@]|E|$]]|$1|O|3|-4|5|6|7|10|8|@]|D|@]|E|$]]]|P|$]]

If you know your value will be in the signed 32 bit integer range, then <code>~~x</code> will do the correct thing in all scenarios.

<pre><code>~~"08" === 8
~~"foobar" === 0
~~(1.99) === 1
~~(-1.99) === -1
</code></pre>

If you look up binary not (<code>~</code>), the spec requires a "ToInt32" conversion for the argument which does the obvious conversion to an Int32 and is specified to coerce <code>NaN</code> values to zero.

Yes, this is incredibly hackish but is so convenient...

blocks|key|342813|text|在parseInt+documentation中，使用可选的基数参数指定基数10：|type|unstyled|depth|inlineStyleRanges|entityRanges|offset|length|data|342814|parseInt('08',+10);+//equals+8
parseInt('09',+10);+//equals+9|code-block|syntax|javascript|342815|这给我的印象是学究、令人困惑和冗长(真的吗，在每个parseInt中都有一个额外的参数？)所以我希望有更好的方法。|342816|entityMap|0|LINK|mutability|MUTABLE|url|https://developer.mozilla.org/en/Core_JavaScript_1.5_Reference/Global_Functions/parseInt^0|1|M|0|0|0|0^^$0|@$1|2|3|4|5|6|7|S|8|@]|9|@$A|T|B|U|1|V]]|C|$]]|$1|D|3|E|5|F|7|W|8|@]|9|@]|C|$G|H]]|$1|I|3|J|5|6|7|X|8|@]|9|@]|C|$]]|$1|K|3|-4|5|6|7|Y|8|@]|9|@]|C|$]]]|L|$M|$5|N|O|P|C|$Q|R]]]]

From the <a href="https://developer.mozilla.org/en/Core_JavaScript_1.5_Reference/Global_Functions/parseInt" rel="noreferrer">parseInt documentation</a>, use the optional radix argument to specify base-10:

<pre><code>parseInt('08', 10); //equals 8
parseInt('09', 10); //equals 9
</code></pre>

This strikes me as pedantic, confusing, and verbose (really, an extra argument in every single parseInt?) so I'm hoping there is a Better Way.

blocks|key|341976|text|function+parseDecimal(s)+{+return+parseInt(s,+10);+}|type|code-block|depth|inlineStyleRanges|entityRanges|data|syntax|javascript|341977|编辑:如果您不喜欢一直在parseInt()调用中添加",10“，那么创建自己的函数来做您真正想做的事情只是一个选择。它的缺点是它是一个非标准函数:如果您经常使用它，对您来说更方便，但对其他人来说可能更令人困惑。|unstyled|341978|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>function parseDecimal(s) { return parseInt(s, 10); }
</code></pre>

edit: making your own function, to do what you really want, is just an option if you don't like adding the ",10" all the time to the parseInt() call. It has the disadvantage of being a nonstandard function: more convenient for you if you use it a lot, but perhaps more confusing for others.

blocks|key|342833|text|指定基数：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|342834|var+number+=+parseInt(s,+10);|code-block|syntax|javascript|342835|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|$]]

Specify the base:

<pre><code>var number = parseInt(s, 10);
</code></pre>

blocks|key|3326511|text|如果parseInt没有第二个参数，用一个假定为十进制的版本替换它会不会很淘气？(注-未测试)|type|unstyled|depth|inlineStyleRanges|entityRanges|data|3326512|parseIntImpl+=+parseInt
parseInt+=+function(str,+base){return+parseIntImpl(str,+base+?+base+:+10)}|code-block|syntax|javascript|3326513|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|$]]

Would it be very naughty to replace parseInt with a version that assumes decimal if it has no second parameter? (note - not tested)

<pre><code>parseIntImpl = parseInt
parseInt = function(str, base){return parseIntImpl(str, base ? base : 10)}
</code></pre>

blocks|key|345354|text|type|unstyled|depth|inlineStyleRanges|entityRanges|data|345355|您也可以使用一元运算符(%2B)，而不是使用parseFloat或parseInt。|blockquote|offset|length|style|BOLD|345356|345357|345358|%2B"01"
//+=>+1

%2B"02"
//+=>+2

%2B"03"
//+=>+3

%2B"04"
//+=>+4

%2B"05"
//+=>+5

%2B"06"
//+=>+6

%2B"07"
//+=>+7

%2B"08"
//+=>+8

%2B"09"
//+=>+9|code-block|syntax|javascript|345359|为了更好的衡量|345360|%2B"09.09"
//+=>+9.09|345361|MDN+Link|345362|345363|一元加号运算符位于其操作数之前，并计算为其操作数，但尝试将其转换为数字(如果尚未转换为数字)。虽然一元取反(-)也可以转换非数字，但一元加是将某些东西转换为数字的最快和首选方法，因为它不对数字执行任何其他操作。|345364|345365|entityMap|0|LINK|mutability|MUTABLE|url|https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Operators/Arithmetic_Operators^0|0|C|1|0|0|0|0|0|0|0|8|0|0|0|1U|E|0|0^^$0|@$1|2|3|-4|4|5|6|16|7|@]|8|@]|9|$]]|$1|A|3|B|4|C|6|17|7|@$D|18|E|19|F|G]]|8|@]|9|$]]|$1|H|3|-4|4|5|6|1A|7|@]|8|@]|9|$]]|$1|I|3|-4|4|5|6|1B|7|@]|8|@]|9|$]]|$1|J|3|K|4|L|6|1C|7|@]|8|@]|9|$M|N]]|$1|O|3|P|4|5|6|1D|7|@]|8|@]|9|$]]|$1|Q|3|R|4|L|6|1E|7|@]|8|@]|9|$M|N]]|$1|S|3|T|4|5|6|1F|7|@]|8|@$D|1G|E|1H|1|1I]]|9|$]]|$1|U|3|-4|4|5|6|1J|7|@]|8|@]|9|$]]|$1|V|3|W|4|C|6|1K|7|@$D|1L|E|1M|F|G]]|8|@]|9|$]]|$1|X|3|-4|4|5|6|1N|7|@]|8|@]|9|$]]|$1|Y|3|-4|4|5|6|1O|7|@]|8|@]|9|$]]]|Z|$10|$4|11|12|13|9|$14|15]]]]

<blockquote>
 You may also, instead of using parseFloat or parseInt, use the unary operator (+).
</blockquote>

<pre><code>+"01"
// =&gt; 1

+"02"
// =&gt; 2

+"03"
// =&gt; 3

+"04"
// =&gt; 4

+"05"
// =&gt; 5

+"06"
// =&gt; 6

+"07"
// =&gt; 7

+"08"
// =&gt; 8

+"09"
// =&gt; 9
</code></pre>

and for good measure

<pre><code>+"09.09"
// =&gt; 9.09
</code></pre>

<a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Operators/Arithmetic_Operators" rel="nofollow noreferrer">MDN Link</a>

<blockquote>
 The unary plus operator precedes its operand and evaluates to its operand but attempts to convert it into a number, if it isn't already. Although unary negation (-) also can convert non-numbers, unary plus is the fastest and preferred way of converting something into a number, because it does not perform any other operations on the number.
</blockquote>

blocks|key|3326537|text|小数是这样的：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|3326538|('09'-0)+===+9++//+true

('009'-0)+===+9+//+true|code-block|syntax|javascript|3326539|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|$]]

How about this for decimal:

<pre><code>('09'-0) === 9 // true

('009'-0) === 9 // true
</code></pre>

blocks|key|340645|text|如果你已经用parseInt编写了一堆代码，并且不想把",+10“加到所有东西上，你可以直接覆盖这个函数，将基数10设为默认值：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|340646|window._oldParseInt+=+window.parseInt;
window.parseInt+=+function(str,+rad)+{
++++if+(!+rad)+{
++++++++return+_oldParseInt(str,+10);
++++}
++++return+_oldParseInt(str,+rad);
};|code-block|syntax|javascript|340647|这可能会使以后的读者感到困惑，因此编写一个parseInt10()函数可能更容易理解。就我个人而言，我更喜欢使用一个简单的函数，而不是必须一直添加",10“-这只会增加出错的机会。|340648|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|$]]

If you've done a bunch of coding already with parseInt and don't want to add ",10" to everything, you can just override the function to make base 10 the default:

<pre><code>window._oldParseInt = window.parseInt;
window.parseInt = function(str, rad) {
 if (! rad) {
 return _oldParseInt(str, 10);
 }
 return _oldParseInt(str, rad);
};
</code></pre>

That may confuse a later reader, so making a parseInt10() function might be more self-explanatory. Personally I prefer using a simple function than having to add ",10" all the time - just creates more opportunity for mistakes.

blocks|key|3113673|text|此问题无法在最新的Chrome或Firefox+(2019)中复制。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|3113674|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|$]]

This issue cannot be replicated in latest Chrome nor Firefox (2019).

Try executing the following in JavaScript:

<pre><code>parseInt('01'); //equals 1
parseInt('02'); //equals 2
parseInt('03'); //equals 3
parseInt('04'); //equals 4
parseInt('05'); //equals 5
parseInt('06'); //equals 6
parseInt('07'); //equals 7
parseInt('08'); //equals 0 !!
parseInt('09'); //equals 0 !!
</code></pre>

I just learned the hard way that JavaScript thinks the leading zero indicates an <a href="http://en.wikipedia.org/wiki/Octal" rel="noreferrer">octal integer</a>, and since there is no <code>"8"</code> or <code>"9"</code> in base-8, the function returns zero. Like it or not, <a href="https://developer.mozilla.org/en/Core_JavaScript_1.5_Reference/Global_Functions/parseInt" rel="noreferrer">this is by design</a>.

What are the workarounds?

Note: For sake of completeness, I'm about to post a solution, but it's a solution that I hate, so please post other/better answers.

<hr>

Update: 

The 5th Edition of the JavaScript standard (<a href="http://www.ecma-international.org/publications/standards/Ecma-262.htm" rel="noreferrer">ECMA-262</a>) introduces a breaking change that eliminates this behavior. Mozilla has a good <a href="https://developer.mozilla.org/en/JavaScript/Reference/Global_Objects/parseInt#ECMAScript_5_Removes_Octal_Interpretation" rel="noreferrer">write-up</a>.

How do I work around JavaScript's parseInt octal behavior?

尝试在JavaScript中执行以下命令：parseInt('01'); //equals 1parseInt('02'); //equals 2parseInt('03'); //equals 3parseInt('04'); //equals 4parseInt('05'); //equals 5parseInt('06'); //equals 6parseInt('07'); //equal

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