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...
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...
isEmpty(null); // => true isEmpty(undefined); // => true 6. 总结 null是JavaScript中的一个特殊值,表示丢失的对象,严格相等运算符确定变量是否为空:variable === null。 typoef运算符对于确定变量的类型(number,string,boolean)很有用。 但是,如果为null,则typeof会产生误导:typeof null的值为'object...
“0? (zero in quotes) is also a truthy value. Falsy Value In JavaScript, the following values are considered to be falsy values: false 0 null “” (empty string) NaN (Not a Number) #ff0000 All other values of JavaScript can be safely assumed to be truthy values. Even an empty ...
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; /...
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....
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。
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"...
true is 1, and false is 0. The string 'Lydia' is a truthy value. What we're actually asking, is "Is this truthy value falsy?". This returns false. 5. Which one is true? const bird = { size: 'small', }; const mouse = { name: 'Mickey', small: true, }; A: mouse.bird...
# 1. Falsy valuesFalsy values is absolutely a must know for JavaScript developers. When I first started learning JS, I made the mistake of trying to memorizing what was "truthy". It always confused me. Did you know an empty array is a truthy value, that always threw me off 🤦♀...