Javascript parseFloat 和 nulls
声明：本页面是StackOverFlow热门问题的中英对照翻译，遵循CC BY-SA 4.0协议，如果您需要使用它，必须同样遵循CC BY-SA许可，注明原文地址和作者信息，同时你必须将它归于原作者（不是我）：StackOverFlow
原文地址: http://stackoverflow.com/questions/15478609/
Warning: these are provided under cc-by-sa 4.0 license. You are free to use/share it, But you must attribute it to the original authors (not me):
StackOverFlow
Javascript parseFloat and nulls
提问by Palendrone
I am very new to javascript as I am currently making a cross platform web app in jQuery Mobile, I have used the example of XML Parsing to a HighCharts graph yet when I encounter a null in my series data it fails to draw any of the line and makes it into a scatter plot almost.
我对 javascript 非常陌生，因为我目前正在 jQuery Mobile 中制作一个跨平台的 Web 应用程序，我已经使用 XML 解析到 HighCharts 图表的示例但是当我在我的系列数据中遇到空值时，它无法绘制任何一条线并使其几乎成为散点图。
// push data points
$(series).find('data point').each(function(i, point) {
seriesOptions.data.push(
parseFloat($(point).text())
);
});
I have no idea how to write a if statement that checks to see if it found a null and if so how to tell it to use it... Can anyone please help or point me in the right direction as I would love my charts to be correct rather than placing a zero value where I have a null.
我不知道如何编写一个 if 语句来检查它是否找到了空值，如果是，如何告诉它使用它......任何人都可以帮助我或指出正确的方向，因为我希望我的图表能够是正确的，而不是在我有一个空值的地方放置一个零值。
采纳答案by Palendrone
With a quick google on Javascript If statments I beleive I have got there - thanks Bjorn :0) Your answer led me to get there !!!
在 Javascript 上快速谷歌一下如果我相信我已经到了那里 - 谢谢 Bjorn :0) 你的回答让我到了那里！
// push data points
$(series).find('data point').each(function(i, point) {
var floatVal = parseFloat($(point).text());
if (!isNaN(floatVal)) {
seriesOptions.data.push(floatVal);
}
else {
seriesOptions.data.push(null);
}
console.log(floatVal)
});
回答by Bj?rn Roberg
Well, parseFloat will return 'NaN' if it's not a number (null and undefined are NaNs) so you could try doing like this:
好吧，如果 parseFloat 不是数字（null 和 undefined 是 NaN），则 parseFloat 将返回“NaN”，因此您可以尝试这样做：
// push data points
$(series).find('data point').each(function(i, point) {
var floatVal = parseFloat($(point).text());
if (!isNaN(floatVal)) {
seriesOptions.data.push(floatVal);
}
});
回答by Grant Thomas
A nullcheck in JavaScript if just like any other C-style language:
一个null在JavaScript中，如果就像任何其他C风格的语言检查：
if (thing == null)
Or
或者
if (thing != null)
I find this works well in most cases against my own programming where I'm writing as I would in, say, C#; however I find other peoples code relies on things never having been declared or set and such and so, and, all in all, it boils down to a spaghetti of checking for nulland "undefined"- yes, the literal string, really - and whatever else.
我发现这在大多数情况下都适用于我自己的编程，就像我在 C# 中编写的那样；但是我发现其他人的代码依赖于从未被声明或设置过的东西等等，总而言之，它归结为检查null和的意大利面条"undefined"- 是的，文字字符串，真的 - 以及其他任何东西。
