Question

function init(){
var panel = document.getElementById("panel");
var i;

var week = ["monday","tuesday","wednesday","thursday","friday"];
var weekend = ["saturday","sunday"];

panel.innerHTML+="weekdays: "+ week;
panel.innerHTML+="<hr>weekend days: "+ weekend;

for(i=0; i<weekend.length; i++)
{
    week[week.length]=weekend[i];
}

panel.innerHTML+="<hr>increased with weekend days: "+week;

week-=2;

panel.innerHTML+="<hr>reduced back to weekdays: "+week;
}
window.onload=init;

这是从另一个html文件加载的主要js代码。一切都很好，直到最后。最后的输出应该减少到工作日：星期一，星期二，星期三，星期四，星期五＆＃34;但是我得到的是这个＆＃34;减少到工作日：NaN＆＃34;，这个错误意味着什么，我该如何解决？

Answer 1

您应该将数组长度减少2，而不是数组本身：

week.length -= 2;

示例：

var week = [1,2,3,4,5,6,7];
week.length -= 2;

console.log(week);
//[1, 2, 3, 4, 5]

Answer 2

您无法从数组中减去数字并期望获得有意义的结果。那就是混合类型，当然行为会很奇怪。

要让周末休息一天，请使用数组对象的pop()方法。

Answer 3

也许你必须改变：

week-=2;

为：

week = week.splice(-2);

编辑（感谢@Esailija）：

splice返回已删除的元素，因此您只需调用splice方法，而无需将结果返回给数组：

week.splice(-2);

Answer 4

function init(){
var panel = document.getElementById("panel");
var i;

var week = ["monday","tuesday","wednesday","thursday","friday"];
var weekend = ["saturday","sunday"];

panel.innerHTML+="weekdays: "+ week;
panel.innerHTML+="<hr>weekend days: "+ weekend;

for(i=0; i<weekend.length; i++)
{
    week[week.length]=weekend[i];
}

panel.innerHTML+="<hr>increased with weekend days: "+week;

week.length -= 2;

panel.innerHTML+="<hr>reduced back to weekdays: "+week;
}
window.onload=init;

但这不是使用.length作为setter的好方法！

JavaScript数组减少

4 个答案: