The result is false if the argument is the empty String (its length is zero); otherwise the result is true Quote taken fromhttp://www.ecma-international.org/publications/files/ECMA-ST/Ecma-262.pdf One caveat警告 is thatnew String("")is truthy! This is because it is an object, whereas ...
1. Undefined and null are always false. 2. Booleans are just treated as booleans (obviously). 3. Numbers are false if they equal 0 or NaN; otherwise, they’re true. 4. Strings are true, except for the empty string "", which is false. 5. Objects are always true. 故事二:各数据类...
Objects include arrays, functions, and ordinary objects. Numbers may be integers or floating point or the special valuesNaNandInfinity. Strings include the empty string,"". Booleans have only two values:trueandfalse. The last two primitive types are a little unusual: the only value whose type ...
字符串类型名:String 布尔类型名:Boolean,取值为true、false 特殊数据 undefined:变量未定义,或定义但未赋值 null: 变量被赋值为空值null 数据类型检测 varmyString='abc'varmyNumber=123dataTpye1=typeofmyStringdataTpye2=typeofmyNumber 返回值: Number String Boolean undefined Object(null数据的返回值) 数据类...
consthome="c:\\temp"; 也可以在换行之前加上反斜杠以转义换行。这样反斜杠和换行都不会出现在字符串的值中。 js conststr="this string \ is broken \ across multiple \ lines.";console.log(str);// this string is broken across multiple lines....
isEmpty({})// trueisEmpty({name:'fatfish'})// false 10.反转字符串 constreverseStr =str=>str.split('').reverse().join('') reverseStr('fatfish')// hsiftaf 11.计算两个日期之间的间隔 constdayDiff =(d1, d2) =>Mat...
some()方法是JavaScript数组的一个内置方法,它对数组中的每个元素都应用一个测试函数,并且在至少有一个元素返回true时返回true,否则返回false。 下面是some()方法的语法: 代码语言:javascript 复制 array.some(function(currentValue, index, arr), thisValue) 参数说明: function(currentValue, index, arr):必需。
Boolean: true or false Number: 1, 6.7, 0xFF String: "Gorilla and banana" Symbol: Symbol("name") (starting ES2015) Null: null Undefined: undefined. And a separatedobject type: {name: "Dmitri"}, ["apple", "orange"]. 从6个基本类型undefined是一个特殊的值,它的类型为Undefined。根据[ECMA...
typeof"John"// Returns string typeof("John"+"Doe")// Returns string typeof3.14// Returns number typeof33// Returns number typeof(33+66)// Returns number typeoftrue// Returns boolean typeoffalse// Returns boolean typeof1234n// Returns bigint ...
使用特定于应用程序的 Office JavaScript API生成外接程序时,请务必包含错误处理逻辑,以考虑运行时错误。 由于 API 的异步性质,这样做至关重要。 最佳做法 在我们的代码示例和Script Lab代码片段中,你会注意到,对、PowerPoint.run或Word.run的每个调用Excel.run都附带一个catch语句来捕获任何错误。 建议在使用特定于...