javascript - 检查 Javascript 中多个变量是 true 还是 false

Question

我有一个处理复选框的函数。我现在正在做的事情是，我想检查 3 个变量是否彼此相等(true 或 false；这并不重要)，如果相等则执行命令。我尝试了几种不同的方向，但无法使其发挥作用。

function dump() {
    var u = document.getElementById("dump").checked;
    var x = document.getElementById("tractor").checked;
    var y = document.getElementById("sweeper").checked;
    var e = document.getElementsByClassName('dump');
    var a = document.getElementsByClassName('tractor');
    var b = document.getElementsByClassName('sweeper');

    for (var i = 0; i < e.length; i++) {
        /*This is the section*/
        if (u==x && x==y)
            e[i].style.display = "block";
            a[i].style.display = "block";
            b[i].style.display = "block";
        /*End*/
        if (u)
            e[i].style.display = "block";
        else
            e[i].style.display = 'none';
        if (x)
            a[i].style.display = "block";
        else
            a[i].style.display = 'none';
        if (y)
            b[i].style.display = "block";
        else
            b[i].style.display = "none";        
    }
} 

已解决

我真正的问题是我需要将该语句移至函数末尾。为了便于测量，我还添加了括号。

function dump() {
    var u = document.getElementById("dump").checked;
    var x = document.getElementById("tractor").checked;
    var y = document.getElementById("sweeper").checked;
    var e = document.getElementsByClassName('dump');
    var a = document.getElementsByClassName('tractor');
    var b = document.getElementsByClassName('sweeper');

    for (var i = 0; i < e.length; i++) {
        if (u){
            e[i].style.display = "block";
        }
        else{
            e[i].style.display = 'none';
        }
        if (x){
            a[i].style.display = "block";
        }
        else{
            a[i].style.display = 'none';
        }
        if (y){
            b[i].style.display = "block";
        }
        else{
            b[i].style.display = "none";        
        }
        if (u==x && x==y){
            e[i].style.display = "block";
            a[i].style.display = "block";
            b[i].style.display = "block";
        }
    }
} 

Answer 1

你需要大括号:

if (u==x && x==y) {
    e[i].style.display = "block";
    a[i].style.display = "block";
    b[i].style.display = "block";
}

否则，if 仅附加到下一个语句，

e[i].style.display = "block"; 

忽略缩进。