Comments (8)
我的代码,还有更短的吗?
function bouncer(arr) { return arr.filter(Boolean); }
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function bouncer(arr) { return arr.filter(function(val){ return Boolean(val); }); }
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我太单纯,还到处找怎么判断NaN
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先弄清filter的用法,课程下面有文档啊。
一句话就搞定弄这么复杂,没弄清原理啊。
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请问能具体解释一下那个最短的代码吗??Boolean直接作为filter判断的参数是怎么回事??
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@Nydia07 filter 接收一个回调函数作为参数,这个回调函数的返回值为 true
或 false
,用来决定元素是否保留。Boolean 是一个 function,返回值是 true
或者 false
。
filter
的回调函数有三个参数,按顺序分别是数组元素、index 和数组本身。而 Boolean
方法只接收一个参数。因此,这里就把数组元素传给了 Boolean()
,然后返回 true
或者 false
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请问能具体解释一下那个最短的代码吗??Boolean直接作为filter判断的参数是怎么回事??
new Boolean([value])
参数
value
可选,用来初始化 Boolean 对象的值。
描述Section
如果第一个参数不是布尔值,则会将其转换为布尔值。如果省略该参数,或者其值为 0、-0、null、false、NaN、undefined、或者空字符串(""),则生成的 Boolean 对象的值为 false。
不要用创建 Boolean 对象的方式将一个非布尔值转化成布尔值,直接将 Boolean 当做转换函数来使用即可:
var x = Boolean(expression); // 推荐
var x = new Boolean(expression); // 不太好
直接写成Boolean的原因是因为function即使没有定义形参,入参也是可以传的。
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最简单做法 return arr.filter( item => {return item ; }
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