在javascript中检查多个条件？

Question

我有一个表格要填写，我想检查所有文本框是否为空，如果它们是空的，则在空的旁边显示星号，如果不是（它们充满信息）提醒页面已保存。

检查部分和显示星号正在工作，保存部分对我不起作用。

function txtchk(tbox, asterisk, f, name) { //the f parameter is an empty paragraph
        var bol = Boolean;
        if (bol === true) {
            if (document.getElementById(tbox).value == "") {
                document.getElementById(asterisk).style.display = "block";
                document.getElementById(f).innerHTML = name + " required";
                document.getElementById(f).style.display = "block";                  
                return bol = true;

            }
            else {
                document.getElementById(asterisk).style.display = "none";
                document.getElementById(f).style.display = "none";
                return bol = false;
            }
        }
        else {
            alert ("saved");
        }
    }

    function combiner() {
        txtchk("tbox1", "asterisk1", "f1", "Product Name");
        txtchk("tbox2", "asterisk2", "f2", "Description");
        txtchk("tbox3", "asterisk3", "f3", "Image");
        txtchk("tbox4", "asterisk4", "f4", "Unit Price");
        txtchk("tbox5", "asterisk5", "f5", "ISBN");
        txtchk("tbox6", "asterisk6", "f6", "Author");
        txtchk("tbox7", "asterisk7", "f7", "Amount in the stock");
        txtchk("tbox8", "asterisk8", "f8", "Color");
        txtchk("ops", "asterisk9", "f9", "Size");
        txtchk("tbox10", "asterisk10", "f10", "Manufacturer");
        txtchk("tbox11", "asterisk11", "f11", "Amount in the stock");
    }

此函数由按钮调用（点击时）

Answer 1

在您当前的代码中，您有以下if 条件：

var bol = Boolean;

if (bol === true) {
        //do something
    }
    else {
        //do something else
    }

问题在于bol 的值将始终相同（一个对象），因此条件bol === true 将始终评估为false。

你想通过这个特定的if 声明来达到什么目的？

Answer 2

看这里...

const checkboxes = [...document.querySelectorAll('label')];
document.querySelector('button').addEventListener('click', () => {
   if(!checkboxes.some(i => i.querySelector('input').checked)){
      if(confirm("No checkbox is checked, add '*'?")){
          checkboxes.forEach(i => {
              const star = document.createElement('span');
              star.innerHTML = "*";
              i.appendChild(star);
          })
      }
   } else {
      const selectedCheckboxes = checkboxes.map(i => i.querySelector('input')).filter(i => i.checked).map(i => i.value);
        alert(JSON.stringify(selectedCheckboxes))
        console.log(JSON.stringify(selectedCheckboxes));
      }
});

label { display: block; }

<h3>Select A choice</h3>
<hr />
<label>
  <input type="checkbox" name="choice" value="Choice 1" /> Choice 1 
</label>
<label>
  <input type="checkbox" name="choice" value="Choice 2" /> Choice 2 
</label>
<label>
  <input type="checkbox" name="choice" value="Choice 3" /> Choice 3 
</label>
<hr />
<button>Submit</button>