Checking forNaNvalues in JavaScript can be tricky, becauseNaNis a special value that represents the result of an invalid or undefined mathematical operation.NaNstands for Not a Number, but its type is actually number. Therefore, we cannot use the usual equality operators (==or===) to compare ...
JavaScript 中用NaN表示的的“Not A Number”概念对于表示错误的数字运算很有用。 即使是NaN本身也不等于任何值。检查变量是否包含NaN的建议方法是使用Number.isNaN(value)。 将字符串形式的数字转换为数字类型失败时,可能会导致显示“Not A Number”。检查parseInt()、parseFloat()或Number()是否返回了NaN是个好主意。
Dealing with the specialNaNvalue can be tricky in JavaScript. It behaves like a number and not a number at the same time. This lesson explains how to identify it using theisNaNfunction or theNumber.isNaNmethod. Number.isNaN = Number.isNaN || function(x) {x !== x} Number.isNaN(NaN...
判断NaN in JavaScript 【NaN 作用是用来表示一个值不是数字】 NaN在JavaScript中行为很怪异,是因为那NaN和任何值都不相等(包括它自己)。 NaN === NaN; // false 因为下面的代码可能会让一些人抓狂: parseInt('hello', 10); // NaN parseInt('hello', 10) == NaN; // false parseInt('hello', 10) ...
JavaScript 中用 NaN 表示的的“Not A Number”概念对于表示错误的数字运算很有用。 即使是 NaN 本身也不等于任何值。检查变量是否包含 NaN 的建议方法是使用 Number.isNaN(value)。 将字符串形式的数字转换为数字类型失败时,可能会导致显示“Not A Number”。检查 parseInt()、parseFloat() 或 Number() 是否返...
NaNis a special value in Javascript, which stands for "Not a Number". If you try to parse a text string in Javascript as anint, you'll get NaN: letx=parseInt("hello")// Returns NaN NaNin itself is kind of confusing, and you don't always get the results you would expect.NaN, fo...
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Let's take a closer look atNaNspecial value: how to check if a variable hasNaN, and importantly understand the scenarios that create "Not A Number" values. 1. NaN number The number type in JavaScript is a set of all number values, including "Not A Number", positive infinity and negative...
代码语言:javascript 复制 if(typeofvariable==='undefined'){// Code to handle undefined value} 3. 检查 NaN: 要检查值是否为 NaN(非数字),可以使用 isNaN() 函数: 代码语言:javascript 复制 if(isNaN(value)){// Code to handle NaN value} ...
1.在screen.textContent = Number(memory + number);行中，您试图将memory和number相加，然后使用Number(...