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POWhen and why number evaluates to NaN, after multiplying, in Javascript?
 

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  1. POWhen and why number evaluates to NaN, after multiplying, in Javascript?
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    <p>From my experience I know, that I can get <code>NaN</code> when doing some division or when trying to make a number out of string, when it actually does not contain a number. Are there any other situations, when I can get a <code>NaN</code>. In particular -- is it possible to get it from multiplication?</p> <p>This is a piece of code, that I use in my PhoneGap application:</p> <pre><code>var g = 9.80665; acceleration.x = (acceleration.x * g).toFixed(2); acceleration.y = (acceleration.y * g).toFixed(2); acceleration.z = ((acceleration.z + 1) * g).toFixed(2); </code></pre> <p>An <code>acceleration</code> is a <a href="http://docs.phonegap.com/en/2.9.0/cordova_accelerometer_accelerometer.md.html#Acceleration" rel="nofollow noreferrer">base PhoneGap object</a> and I can hardly believe, that it contains a string or any other value, except float, that could result in a <code>NaN</code>.</p> <p>However, in some certain situations (on some specific devices) I'm getting a <code>NaN</code> out of above.</p> <p>It isn't a problem for me to "secure" above values with a code like this:</p> <pre><code>acceleration.x = (parseFloat(acceleration.x) || 0) + ' m/s\u00b2'; acceleration.y = (parseFloat(acceleration.y) || 0) + ' m/s\u00b2'; acceleration.z = (parseFloat(acceleration.z) || 0) + ' m/s\u00b2'; </code></pre> <p>But, I'm really curious, when and why I can get a <code>NaN</code> after doing just a multiply of some values?</p> <p>BTW: I've read <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/isNaN#Description" rel="nofollow noreferrer">this</a> at MDN, as good as <a href="https://stackoverflow.com/questions/12227594/which-is-better-numberx-or-parsefloatx">many</a> <a href="https://stackoverflow.com/questions/3215120/why-javascript-says-that-a-number-is-not-a-number">related</a> <a href="https://stackoverflow.com/questions/559792/what-is-the-reserved-keyword-for-nan-in-javascript">answers</a> <a href="https://stackoverflow.com/questions/6678596/nan-is-a-number">here</a> at Stack Overflow, but to brought me no help or answer to my question.</p>
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    1. COWhy not also post a console.log of the acceleration object (or at least the relevant properties)? Right now, the only thing that I'm seeing is "one of those properties is undefined"
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    2. CO@Stephen: I can't post console.log for this, because (as I wrote) it happens only in certain situations (on certain mobile devices). Beside, the question was "_when I can get `NaN` out of multiplication in Javascript_", not "_what is wrong with my PhoneGap code_". Maybe I should ask this at "Programmers"?
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