小于和大于10 [英] Less than and greater than 10
问题描述
我正在进行随机代码挑战,我无法弄清楚我的生活将如何实现这一目标
I'm working on a random code challenge, and I cannot figure out for the life of me how this would be possible
function(obj) {
if ( (obj < 10) && (obj > 10) ) {
return true;
}
}
我尝试过的事情是设置一个间隔来改变变量为0ms(最终成为浏览器默认值),使obj成为一个生命函数,每次使用时都会递增一个全局变量,以及一大堆其他看似不太有用的方法。这里有什么想法,或者指出一些我不知道明显的东西?
Things I've tried are setting an interval to change the variable at 0ms(which ends up being browser default), making obj an life function that increments a global variable every time it's used, and a whole bunch of other seemingly less useful approaches. Any ideas here, or pointers for something obvious I'm missing?
推荐答案
线索在变量名称obj中。比较对象时,他们的 valueOf()<调用/ code>
方法。如果我们提供 valueOf
方法,每次都返回一个不同的值:
The clue is in the variable name "obj". When objects are compared, their valueOf()
method is called. If we supply a valueOf
method that returns a different value every time:
function test(obj) {
if ( (obj < 10) && (obj > 10) ) {
return true;
}
}
var Obj = function() {
var flag = false;
this.valueOf = function() {
if( flag ) {
return 11;
}
flag = true;
return 9;
}
}
console.log( test( new Obj() ) );
上述对象的 toValue
在第一次调用时返回9(9 <10),从那时开始返回11(11> 10)。
The above object's toValue
returns 9 the first time it's called (9 < 10) and 11 from then on (11 > 10).
这篇关于小于和大于10的文章就介绍到这了,希望我们推荐的答案对大家有所帮助,也希望大家多多支持IT屋!