D: 全都是 of them are falsy 答案: A 只有6 种 falsy 值: undefined null NaN 0 '' (empty string) false Function 构造函数, 比如 new Number 和new Boolean,是 truthy。 36. 输出是什么? console.log(typeof typeof 1) A: "number" B: "string" C: "object" D: "undefined" 答案: B typ...
Falsy值包括:false、undefined、null、正负0、NaN、""。 2.其余所有的值均为Truthy,当进行逻辑判断时均为true。值得注意的是,Infinity、空数组、”0″都是Truthy值。 varx = "0";if(x){"string 0 is Truthy."}else{"string 0 is Falsy."}vary =[];if(y){"empty array is Truthy."}else{"empty a...
false 0 "" (empty string) null undefined NaNHere are examples of boolean context:if condition evaluation if (myVar) {}myVar can be any first-class citizen (variable, function, boolean) but it will be casted into a boolean because it's evaluated in a boolean context....
只有8 种 falsy 值: undefined null NaN false '' (empty string) 0 -0 0n (BigInt(0)) Function 构造函数,比如 new Number 和new Boolean,是 truthy。 36. 输出是什么? console.log(typeof typeof 1) A: "number" B: "string" C: "object" D: "undefined" 答案 答案:B typeof 1 返回"...
if (1 && 0) { // 作为 true && false 来执行alert( "won't work, because the result is falsy" );} 与操作寻找第一个假值 给出多个参加与运算的值: result = value1 && value2 && value3; 与运算&&做了如下的事: 从左到右依次计算操作数。
console.log('null is falsy') } 2.2 typeof null typeof value运算符确定值的类型。 例如,typeof 15是'number',typeof {prop:'Value'}的计算结果是'object'。 有趣的是,type null的结果是什么 typeof null; // => 'object' 为什么是'object',typoef null为object是早期 JS 实现中的一个错误。
log('null is truthy') } else { console.log('null is falsy') } 2.2 typeof null typeof value运算符确定值的类型。 例如,typeof 15是'number',typeof {prop:'Value'}的计算结果是'object'。 有趣的是,type null的结果是什么 代码语言:javascript 代码运行次数:0 运行 AI代码解释 typeof null; /...
8年前 react Updated "how to define propTypes..." 8年前 .editorconfig Add editorconfig 9年前 .gitignore Only apps should have lockfiles. 8年前 .npmrc Only apps should have lockfiles. 8年前 .travis.yml [eslint config] [deps] allow eslint v3 or v4 8年前 LICENSE.md...
When a value for a property is blank (empty string, null, or undefined), that property is removed. When a unitless number value is given, “px” is appended to it for properties that require units. var elem = $('h1') elem.css('background-color') // read property elem.css('backgr...
The name of anonymous function expressions is the empty string: > var f2 = function () {}; > f2.name '' Named function expressions, however, do have a name: > var f3 = function myName() {}; > f3.name 'myName' The name of a function is useful for debugging. Some people always...