blocks|key|1020740|text|你有这句台词|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1020741|dots+=+document.getElementById("txt").value;|code-block|syntax|javascript|1020742|在您的文件中，这会将点设置为字符串，因为txt的内容不限于数字。|1020743|要将其转换为int类型，请将该行更改为：|1020744|dots+=+parseInt(document.getElementById("txt").value,+10);|1020745|注意:这里的10指定十进制(基数为10)。如果没有这一点，一些浏览器可能无法正确解释字符串。参见MDN：parseInt。|offset|length|style|CODE|1020746|entityMap|0|LINK|mutability|MUTABLE|url|https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/parseInt#Description^0|0|0|0|0|0|6|2|1G|8|1G|8|0|0^^$0|@$1|2|3|4|5|6|7|10|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|11|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|12|8|@]|9|@]|A|$]]|$1|I|3|J|5|6|7|13|8|@]|9|@]|A|$]]|$1|K|3|L|5|D|7|14|8|@]|9|@]|A|$E|F]]|$1|M|3|N|5|6|7|15|8|@$O|16|P|17|Q|R]|$O|18|P|19|Q|R]]|9|@$O|1A|P|1B|1|1C]]|A|$]]|$1|S|3|-4|5|6|7|1D|8|@]|9|@]|A|$]]]|T|$U|$5|V|W|X|A|$Y|Z]]]]

You have the line 

<pre><code>dots = document.getElementById("txt").value;
</code></pre>

in your file, this will set dots to be a string because the contents of txt is not restricted to a number.

to convert it to an int change the line to:

<pre><code>dots = parseInt(document.getElementById("txt").value, 10);
</code></pre>

Note: The <code>10</code> here specifies decimal (base-10). Without this some browsers may not interpret the string correctly. See MDN: <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/parseInt#Description" rel="noreferrer"><code>parseInt</code></a>.

blocks|key|1020772|text|最简单的：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1020773|dots+=+dots*1%2B5;|code-block|syntax|javascript|1020774|这些点将被转换为数字。|1020775|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|$]]

the simplest:

<pre><code>dots = dots*1+5;
</code></pre>

the dots will be converted to number.

blocks|key|806187|text|别忘了-如果你要处理小数，就使用parseFloat();。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|806188|entityMap^0|G|D|0^^$0|@$1|2|3|4|5|6|7|H|8|@$9|I|A|J|B|C]]|D|@]|E|$]]|$1|F|3|-4|5|6|7|K|8|@]|D|@]|E|$]]]|G|$]]

DON'T FORGET - Use <code>parseFloat();</code> if your dealing with decimals.

blocks|key|806417|text|我添加这个答案是因为我在这里看不到它。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|806418|一种方法是在值的前面放一个'%2B‘字符|806419|示例：|806420|var+x+=+%2B'11.5'+%2B+%2B'3.5'|code-block|syntax|javascript|806421|X+===+15|806422|我发现这是最简单的方法|806423|在本例中，这一行：|806424|dots+=+document.getElementById("txt").value;|806425|可以更改为|806426|dots+=+%2B(document.getElementById("txt").value);|806427|将其强制转换为一个数字|806428|注意：|806429|%2B''+===+0
%2B[]+===+0
%2B[5]+===+5
%2B['5']+===+5|806430|entityMap^0|0|0|0|0|0|0|0|0|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|14|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|15|8|@]|9|@]|A|$]]|$1|D|3|E|5|6|7|16|8|@]|9|@]|A|$]]|$1|F|3|G|5|H|7|17|8|@]|9|@]|A|$I|J]]|$1|K|3|L|5|6|7|18|8|@]|9|@]|A|$]]|$1|M|3|N|5|6|7|19|8|@]|9|@]|A|$]]|$1|O|3|P|5|6|7|1A|8|@]|9|@]|A|$]]|$1|Q|3|R|5|H|7|1B|8|@]|9|@]|A|$I|J]]|$1|S|3|T|5|6|7|1C|8|@]|9|@]|A|$]]|$1|U|3|V|5|H|7|1D|8|@]|9|@]|A|$I|J]]|$1|W|3|X|5|6|7|1E|8|@]|9|@]|A|$]]|$1|Y|3|Z|5|6|7|1F|8|@]|9|@]|A|$]]|$1|10|3|11|5|H|7|1G|8|@]|9|@]|A|$I|J]]|$1|12|3|-4|5|6|7|1H|8|@]|9|@]|A|$]]]|13|$]]

I'm adding this answer because I don't see it here.

One way is to put a '+' character in front of the value

example:

<pre><code>var x = +'11.5' + +'3.5'
</code></pre>

x === 15

I have found this to be the simplest way

In this case, the line:

<pre><code>dots = document.getElementById("txt").value;
</code></pre>

could be changed to 

<pre><code>dots = +(document.getElementById("txt").value);
</code></pre>

to force it to a number

NOTE: 

<pre><code>+'' === 0
+[] === 0
+[5] === 5
+['5'] === 5
</code></pre>

blocks|key|806231|text|parseInt()应该可以做到这一点|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|806232|var+number+=+"25";
var+sum+=+parseInt(number,+10)+%2B+10;
var+pin+=+number+%2B+10;|code-block|syntax|javascript|806233|为您提供|806234|sum+==+35
pin+==+"2510"|806235|http://www.w3schools.com/jsref/jsref_parseint.asp|806236|注意：parseInt(number,+10)中的10指定十进制(基数为10)。如果没有这一点，一些浏览器可能无法正确解释字符串。参见MDN：parseInt。|806237|entityMap|0|LINK|mutability|MUTABLE|url|1|https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/parseInt#Description^0|0|A|0|0|0|0|0|1D|0|0|3|K|P|2|1Z|8|1Z|8|1|0^^$0|@$1|2|3|4|5|6|7|11|8|@$9|12|A|13|B|C]]|D|@]|E|$]]|$1|F|3|G|5|H|7|14|8|@]|D|@]|E|$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|P|5|6|7|17|8|@]|D|@$9|18|A|19|1|1A]]|E|$]]|$1|Q|3|R|5|6|7|1B|8|@$9|1C|A|1D|B|C]|$9|1E|A|1F|B|C]|$9|1G|A|1H|B|C]]|D|@$9|1I|A|1J|1|1K]]|E|$]]|$1|S|3|-4|5|6|7|1L|8|@]|D|@]|E|$]]]|T|$U|$5|V|W|X|E|$Y|P]]|Z|$5|V|W|X|E|$Y|10]]]]

<code>parseInt()</code> should do the trick

<pre><code>var number = "25";
var sum = parseInt(number, 10) + 10;
var pin = number + 10;
</code></pre>

Gives you

<pre><code>sum == 35
pin == "2510"
</code></pre>

<a href="http://www.w3schools.com/jsref/jsref_parseint.asp" rel="nofollow noreferrer">http://www.w3schools.com/jsref/jsref_parseint.asp</a>

Note: The <code>10</code> in <code>parseInt(number, 10)</code> specifies decimal (base-10). Without this some browsers may not interpret the string correctly. See MDN: <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/parseInt#Description" rel="nofollow noreferrer"><code>parseInt</code></a>.

blocks|key|1021041|text|这也适用于你：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1021042|dots+-=+-5;|code-block|syntax|javascript|1021043|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|$]]

This also works for you: 

<pre><code>dots -= -5;
</code></pre>

blocks|key|806512|text|您可以在变量后面添加%2B，它将强制变量为整数|type|unstyled|depth|inlineStyleRanges|entityRanges|data|806513|var+dots+=+5
++++function+increase(){
++++++++dots+=+%2Bdots+%2B+5;
++++}|code-block|syntax|javascript|806514|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|$]]

You can add + behind the variable and it will force it to be an integer

<pre><code>var dots = 5
 function increase(){
 dots = +dots + 5;
 }
</code></pre>

blocks|key|806575|text|Number()|type|unstyled|depth|inlineStyleRanges|entityRanges|offset|length|data|806576|dots+=+document.getElementById("txt").value;
dots+=+Number(dots)+%2B+5;|code-block|syntax|javascript|806577|//+from+MDN
Number('123')+++++//+123
Number('123')+===+123+///+true
Number('12.3')++++//+12.3
Number('12.00')+++//+12
Number('123e-1')++//+12.3
Number('')++++++++//+0
Number(null)++++++//+0
Number('0x11')++++//+17
Number('0b11')++++//+3
Number('0o11')++++//+9
Number('foo')+++++//+NaN
Number('100a')++++//+NaN
Number('-Infinity')+//-Infinity|806578|entityMap|0|LINK|mutability|MUTABLE|url|https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Number#Convert_numeric_strings_and_null_to_numbers^0|0|8|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]]|$1|I|3|J|5|F|7|X|8|@]|9|@]|C|$G|H]]|$1|K|3|-4|5|6|7|Y|8|@]|9|@]|C|$]]]|L|$M|$5|N|O|P|C|$Q|R]]]]

<a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Number#Convert_numeric_strings_and_null_to_numbers" rel="nofollow noreferrer">Number()</a>
<pre class="lang-js prettyprint-override"><code>dots = document.getElementById(&quot;txt&quot;).value;
dots = Number(dots) + 5;

</code></pre>
<pre class="lang-js prettyprint-override"><code>// from MDN
Number('123') // 123
Number('123') === 123 /// true
Number('12.3') // 12.3
Number('12.00') // 12
Number('123e-1') // 12.3
Number('') // 0
Number(null) // 0
Number('0x11') // 17
Number('0b11') // 3
Number('0o11') // 9
Number('foo') // NaN
Number('100a') // NaN
Number('-Infinity') //-Infinity
</code></pre>

blocks|key|806495|text|这真的很简单|type|unstyled|depth|inlineStyleRanges|entityRanges|data|806496|var+total+=+(1+*+yourFirstVariablehere)+%2B+(1+*+yourSecondVariablehere)|code-block|syntax|javascript|806497|这迫使javascript倍增，因为在javascript中没有*+sign的混淆。|806498|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|$]]

its really simple just

<pre><code>var total = (1 * yourFirstVariablehere) + (1 * yourSecondVariablehere)
</code></pre>

this forces javascript to multiply because there is no confusion for * sign in javascript.

blocks|key|1021251|text|在针对我的特定案例尝试了这里的大多数答案但都没有成功之后，我得出了以下结论：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1021252|dots+=+-(-dots+-+5);|code-block|syntax|javascript|1021253|%2B号是混淆js的原因，这完全消除了它们。实现起来很简单，但理解起来可能会让人感到困惑。|1021254|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|$]]

After trying most of the answers here without success for my particular case, I came up with this:

<pre><code>dots = -(-dots - 5);
</code></pre>

The + signs are what confuse js, and this eliminates them entirely. Simple to implement, if potentially confusing to understand.

blocks|key|1020963|text|自上一次投票否决后更新...|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1020964|我只看到了那部分|1020965|var+dots+=+5
function+increase(){
++++dots+=+dots%2B5;
}|code-block|syntax|javascript|1020966|之前，但后来向我展示了txt框提供给变量dots。因此，您需要确保“清理”输入，以确保它只包含整数，而不是恶意代码。|offset|length|style|CODE|1020967|一种简单的方法是使用onkeyup()事件解析textbox，以确保它包含数字字符：|1020968|<input+size="40"+id="txt"+value="Write+a+character+here!"+onkeyup="GetChar+(event);"/>|1020969|其中，如果值不是数字，则事件将给出错误并清除最后一个字符：|1020970|<script+type="text/javascript">
++++function+GetChar+(event){
++++++++var+keyCode+=+('which'+in+event)+?+event.which+:+event.keyCode;
++++++++var+yourChar+=+String.fromCharCode();
++++++++if+(yourChar+!=+"0"+&&
++++++++++++yourChar+!=+"1"+&&
++++++++++++yourChar+!=+"2"+&&
++++++++++++yourChar+!=+"3"+&&+
++++++++++++yourChar+!=+"4"+&&
++++++++++++yourChar+!=+"5"+&&
++++++++++++yourChar+!=+"6"+&&+
++++++++++++yourChar+!=+"7"+&&
++++++++++++yourChar+!=+"8"+&&+
++++++++++++yourChar+!=+"9")
++++++++{
++++++++++++alert+('The+character+was+not+a+number');
++++++++++++var+source+=+event.target+%7C%7C+event.srcElement;
++++++++++++source.value+=+source.value.substring(0,source.value-2);
++++++++}
++++}
</script>|1020971|显然，使用regex也可以做到这一点，但我选择了懒惰的方式。|1020972|从那时起，您就知道盒子里只能有数字了，您应该能够只使用eval()|1020973|dots+=+eval(dots)+%2B+5;|1020974|entityMap^0|0|0|0|B|3|K|4|0|A|9|0|0|0|0|0|R|6|0|0^^$0|@$1|2|3|4|5|6|7|14|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|15|8|@]|9|@]|A|$]]|$1|D|3|E|5|F|7|16|8|@]|9|@]|A|$G|H]]|$1|I|3|J|5|6|7|17|8|@$K|18|L|19|M|N]|$K|1A|L|1B|M|N]]|9|@]|A|$]]|$1|O|3|P|5|6|7|1C|8|@$K|1D|L|1E|M|N]]|9|@]|A|$]]|$1|Q|3|R|5|F|7|1F|8|@]|9|@]|A|$G|H]]|$1|S|3|T|5|6|7|1G|8|@]|9|@]|A|$]]|$1|U|3|V|5|F|7|1H|8|@]|9|@]|A|$G|H]]|$1|W|3|X|5|6|7|1I|8|@]|9|@]|A|$]]|$1|Y|3|Z|5|6|7|1J|8|@$K|1K|L|1L|M|N]]|9|@]|A|$]]|$1|10|3|11|5|F|7|1M|8|@]|9|@]|A|$G|H]]|$1|12|3|-4|5|6|7|1N|8|@]|9|@]|A|$]]]|13|$]]

UPDATED since this was last downvoted....

I only saw the portion 

<pre><code>var dots = 5
function increase(){
 dots = dots+5;
}
</code></pre>

before, but it was later shown to me that the <code>txt</code> box feeds the variable <code>dots</code>. Because of this, you will need to be sure to "cleanse" the input, to be sure it only has integers, and not malicious code.

One easy way to do this is to parse the textbox with an <code>onkeyup()</code> event to ensure it has numeric characters:

<pre><code>&lt;input size="40" id="txt" value="Write a character here!" onkeyup="GetChar (event);"/&gt;
</code></pre>

where the event would give an error and clear the last character if the value is not a number:

<pre><code>&lt;script type="text/javascript"&gt;
 function GetChar (event){
 var keyCode = ('which' in event) ? event.which : event.keyCode;
 var yourChar = String.fromCharCode();
 if (yourChar != "0" &amp;&amp;
 yourChar != "1" &amp;&amp;
 yourChar != "2" &amp;&amp;
 yourChar != "3" &amp;&amp; 
 yourChar != "4" &amp;&amp;
 yourChar != "5" &amp;&amp;
 yourChar != "6" &amp;&amp; 
 yourChar != "7" &amp;&amp;
 yourChar != "8" &amp;&amp; 
 yourChar != "9")
 {
 alert ('The character was not a number');
 var source = event.target || event.srcElement;
 source.value = source.value.substring(0,source.value-2);
 }
 }
&lt;/script&gt;
</code></pre>

Obviously you could do that with regex, too, but I took the lazy way out.

Since then you would know that only numbers could be in the box, you should be able to just use <code>eval()</code>:

<pre><code>dots = eval(dots) + 5;
</code></pre>

I need javascript to add 5 to an integer variable, but instead it treats the variable as a string, so it write out the variable, then add 5 onto the end of the "string". How can I force it to do math instead?

<pre><code>var dots = document.getElementById("txt").value; // 5
function increase(){
 dots = dots + 5;
}
</code></pre>

Output: <code>55</code>

How can I force it to output <code>10</code>?

How to force JS to do math instead of putting two strings together

我需要javascript把5加到一个整型变量上，但是它把变量当作字符串，所以写出变量，然后把5加到" string“的末尾。我怎么才能强迫它去做数学呢？var dots = document.getElementById("txt").value; // 5function increase(){    dots = dots + 5;}输出：55如何强制它输出10？

问如何强制JS进行数学运算，而不是将两个字符串放在一起
EN

回答 11

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问如何强制JS进行数学运算，而不是将两个字符串放在一起EN

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问如何强制JS进行数学运算，而不是将两个字符串放在一起
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