Node.JS/Javascript - 将字符串转换为整数会在我不希望它返回 NaN 时返回
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Node.JS/Javascript - casting string to integer is returning NaN when I wouldn't expect it to
提问by PinkElephantsOnParade
This is all in the context of a larger program, so Im going to try keep it simple, showing the offending lines only. I have an array of values that are numbers in string form a la "84", "32", etc.
这都是在一个更大的程序的上下文中，所以我会尽量保持简单，只显示有问题的行。我有一个值数组，这些值是字符串形式的数字，例如“84”、“32”等。
Yet THIS line
然而这条线
console.log(unsolved.length + " " + unsolved[0] + " " + parseInt(unsolved[0]) + " " + parseInt("84"));
prints:
印刷：
4 "84" NaN 84
"84" is the array element Im trying to parseInt! Yet it won't work unless I take it out of the context of an array and have it explicitly written. What's going on?
“84”是我试图解析的数组元素！然而，除非我把它从数组的上下文中取出并明确地写出来，否则它不会工作。这是怎么回事？
采纳答案by Alex W
You can try removing the quotations from the string to be processed using this function:
您可以尝试使用此函数从要处理的字符串中删除引号：
function stripAlphaChars(source) {
var out = source.replace(/[^0-9]/g, '');
return out;
}
Also you should explicitly specify that you want to parse a base 10 number:
此外，您应该明确指定要解析以 10 为基数的数字：
parseInt(unsolved[0], 10);
回答by lanzz
parseIntwould take everything from the start of its argument that looks like a number, and disregard the rest. In your case, the argument you're calling it with starts with ", so nothing looks like a number, and it tries to cast an empty string, which is really not a number.
parseInt将从它的参数开始处取所有看起来像数字的东西，而忽略其余部分。在你的情况下，你调用它的参数以 开头"，所以没有什么看起来像一个数字，它试图转换一个空字符串，它实际上不是一个数字。
回答by Saebekassebil
You should make sure that the array element is indeed a string which is possible to parse to a number. Your array element doesn't contain the value '84', but actually the value '"84"'(a string containing a number encapsulated by ")
您应该确保数组元素确实是一个可以解析为数字的字符串。您的数组元素不包含 value '84'，但实际上包含 value '"84"'（包含由 " 封装的数字的字符串）
You'll want to remove the "from your array elements, possible like this:
您需要"从数组元素中删除，可能如下所示：
function removeQuotationMarks(string) {
return (typeof string === 'string') ? string.replace(/"|'/g, '') : string;
}
unsolved = unsolved.map(removeQuotationMarks);
Now all the array elements should be ready to be parsed with parseInt(unsolved[x], 10)
现在所有的数组元素都应该准备好被解析了 parseInt(unsolved[x], 10)
回答by KARTHIKEYAN.A
First we need to replace " to ' in give data using Regex and replace and then we need to cast.
首先，我们需要使用正则表达式和替换在给定数据中将 " 替换为 ' ，然后我们需要进行转换。
var i = 1;
var j = "22"
function stringToNumber(n) {
return (typeof n === 'string') ? parseInt(Number(n.replace(/"|'/g, ''))) : n;
}
console.log(stringToNumber(i)); // 1
console.log(stringToNumber(j)); // 22