将三个选择菜单中的元素切入和切出数组

Question

var select1 = document.getElementById('select1');
var select2 = document.getElementById('select2');
var array = [];
let sel1 = false;

function myFunct1() { 
  var one = select1.options[select1.selectedIndex].value;
  if(array.length === 1 && !sel1) array.unshift(one);
  else array.splice(0,1,one);
  console.log(array);
  sel1 = true;
}

function myFunct2() {
  var two = select2.options[select2.selectedIndex].value;
  array.splice(sel1, 1, two);
  console.log(array);
}

            function myFunct3() {
                var three = select3.options[select3.selectedIndex].value;
            }

<select id = 'select1' onchange = 'myFunct1()'>
            <option disabled selected value> -- select an option -- </option>
            <option value = 'Dog1'>Dog</option>
            <option value = 'Cat1'>Cat</option>
            <option value = 'Bear1'>Bear</option>
            </select>
            
        <select id = 'select2' onchange = 'myFunct2()'>
            <option disabled selected value> -- select an option -- </option>
            <option value = 'Dog2'>Dog</option>
            <option value = 'Cat2'>Cat</option>
            <option value = 'Bear2'>Bear</option>
            </select>
                    
        <select id = 'select3' onchange = 'myFunct3()'>
            <option disabled selected value> -- select an option -- </option>
            <option value = 'Dog3'>Dog</option>
            <option value = 'Cat3'>Cat</option>
            <option value = 'Bear3'>Bear</option>
            </select>

我有这个方法，使用两个选择菜单完全符合我的要求。因此，如果从第二个选择中连续选择两次，则在从第一个选择之前，数组的长度永远不会超过一个。现在我想要合并第三个选择菜单。请帮我做这个工作。我知道我可以将它们全部合并到一个功能中而不必处理这些问题，但是对于我的使用，我不能那样做。主要条件是数组中从同一个选择菜单中永远不会有多个选择，并且数组中的任何空位置都不会计入其长度。所以不会出现[undefined，Cat2]数组。

Answer 1

简单的方法是：

• 创建两个数组，即realArr（以保持原始索引处的字符串）。例如，来自select1的值将始终设置为realArr[0]，并从select2设置为realArr[1] ...
• 第二个数组showArr是使用undefined从中删除filter()的数组

var select1 = document.getElementById('select1');
        var select2 = document.getElementById('select2');
        var select3= document.getElementById('select3');
        var realArr = [];
        var showArr = [];
        
        function myFunct1() { 
            var one = select1.options[select1.selectedIndex].value;
            realArr[0] = one;
            showArr = realArr.filter(x => x !== undefined);
            console.log(showArr);
        }
        
        function myFunct2() {
            var two = select2.options[select2.selectedIndex].value;
            realArr[1] = two
            showArr = realArr.filter(x => x !== undefined);
            console.log(showArr);
        }


        function myFunct3() {
            var three = select3.options[select3.selectedIndex].value;
            realArr[2] = three;
            showArr = realArr.filter(x => x !== undefined);
            console.log(showArr);
        }

<select id = 'select1' onchange = 'myFunct1()'>
        <option disabled selected value> -- select an option -- </option>
        <option value = 'Dog1'>Dog</option>
        <option value = 'Cat1'>Cat</option>
        <option value = 'Bear1'>Bear</option>
        </select>
        
    <select id = 'select2' onchange = 'myFunct2()'>
        <option disabled selected value> -- select an option -- </option>
        <option value = 'Dog2'>Dog</option>
        <option value = 'Cat2'>Cat</option>
        <option value = 'Bear2'>Bear</option>
        </select>
                
    <select id = 'select3' onchange = 'myFunct3()'>
        <option disabled selected value> -- select an option -- </option>
        <option value = 'Dog3'>Dog</option>
        <option value = 'Cat3'>Cat</option>
        <option value = 'Bear3'>Bear</option>
        </select>