// NaN出现的原因:(Not a Number) // 操作两个类型不一致的数、用NaN值计算最终得到NaN、不合法运算(如0 / 0) let num = 0/0;if(isNaN(num)) { console.log("num为NaN!") } 2. 判断undefined let temp =undefined//方法一if(typeof(temp) == "undefined") { console.log("temp is undefined...
Else if O has a [[BooleanData]] internal slot, let builtinTag be "Boolean". Else if O has a [[NumberData]] internal slot, let builtinTag be "Number". Else if O has a [[DateValue]] internal slot, let builtinTag be "Date". Else if O has a [[RegExpMatcher]] internal slot,...
Number 数据类型是有范围的,但是不需要我们刻意去计,记住它的关键字就可以了。 最后再说一个关键字:NaN:not a number,这个表示不是数值,当有两个数据运算时,运算失败就会返回这个值。我们也可以判断一个数据类型是不是 NaN,使用isNaN()方法即可。 4.2 String String 类型就是用单引号或双引号括起来的内容就是...
(2)若使用全等 “===” ,比较的是值和数据类型,只有全都相同才返回 true 八、Number(数字) Number类型用来表示整数值和浮点数值,还有一种特殊的数值,即NaN(非数值 Not a Number)。 8.1 整数值 整数值可以是正整数、负整数和0。 它们可通过以 10 为基数(十进制)、以 16 为基数(十六进制)和以 8 为基...
If a number is supplied, delay is applied to both hide/show Object structure is: delay: { "show": 500, "hide": 100 } html boolean false Insert HTML into the tooltip. If false, jQuery's text method will be used to insert content into the DOM. Use text if you're worried about XSS...
Using the name cache is not necessary if you compress all your files in a single call to Terser. Mangling unquoted names (--mangle-props keep_quoted) Using quoted property name (o["foo"]) reserves the property name (foo) so that it is not mangled throughout the entire script even when...
If you have a large screen, the menu will always be present on the left. If you have a small screen, open the menu by clicking the top menu sign☰. Learn by Examples Examples are better than 1000 words. Examples are often easier to understand than text explanations. ...
type oldType = number; -type newType = oldType; -const x: newType = 5; +const x: oldType = 5;remove duplicate interface keys interface Hello { - 'hello': any; 'hello': string; }remove unused types type n = number; -type s = string; const x: n = 5;apply...
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...
You can use the global JavaScript functionisNaN()to find out if a value is a not a number: Example letx =100/"Apple"; isNaN(x); Try it Yourself » Watch out forNaN. If you useNaNin a mathematical operation, the result will also beNaN: ...