我正在尝试学习如何使用JS和HTML动态创建对象并将函数应用于它们。如何使用<select>下拉列表的文本/值尽可能直接地调用对象上的函数？过去我在数组、if-then语句或条件链中使用过函数，但这似乎是额外的工作。
我也愿意接受关于动态对象实例创建的建议，因为我不确定这个例子中的方法是否是最佳实践。
这是我的例子：
HTML
<!DOCTYPE html>
<html>
<head>
</head>
<body>
<input id="name" placeholder="name">
<button id="new">add new object</button>
<br>
<input id="property" placeholder="property value">
<select id="functions">
<option>apply a function</option>
<option value="myFunction()">sum</option>
<option value="myFunction2()">multiply</option>
</select>
</body>
<script src="dynamic-objects.js"></script>
</html>
JS-
// Class and its functions
function myClass() {
this.existingProperty = 5
}
myClass.prototype.myFunction = function () {
this.resultProperty = this.newProperty + this.existingProperty
}
myClass.prototype.myFunction2 = function () {
this.resultProperty = this.newProperty * this.existingProperty
}
// Memory
const locoParentis = []
let nameField = ''
let propField = 0
// Name of object instance of myClass (for example: type dogs into the brower/HTML "name" input)
document.querySelector('#name').addEventListener('change', (e)=>{
nameField = e.target.value
})
// Add the new objeect instance to the array (for example: click add new object to create an object called dogs with an existingProperty of 5)
document.querySelector('#new').addEventListener('click', ()=>{
locoParentis[nameField] = new myClass()
console.log(locoParentis)
})
// Create/set new property in object instance (for example: typing 9 in the property value input sets dogs' newProperty to 9)
document.querySelector('#property').addEventListener('input', (e)=>{
locoParentis[nameField].newProperty = Number(e.target.value)
console.log(locoParentis)
})
// Apply prototypical functions on object instance (for example: chosing sum outputs 14 into the console.)
document.querySelector('#functions').addEventListener('change', (e)=>{
console.log(e.target.value)
//HOW CAN I CHANGE THIS INTO SOMETHING LIKE locoParentis[nameField].e.target.value()
e.target.value === "myFunction()" ? locoParentis[nameField].myFunction() : locoParentis[nameField].myFunction2()
console.log(locoParentis[nameField].resultProperty)
})
描述：我可以通过在名称<input>中键入名称来动态创建myClass的新对象实例，但我想对<select>和myClass的原型函数使用类似的方法。
// Class and its functions
function myClass() {
this.existingProperty = 5;
}
myClass.prototype.myFunction = function () {
this.resultProperty = this.newProperty + this.existingProperty;
}
myClass.prototype.myFunction2 = function () {
this.resultProperty = this.newProperty * this.existingProperty;
}
// Memory
const locoParentis = {};
let nameField;
// Name of object instance of myClass (for example: type dogs into the brower/HTML "name" input)
document.querySelector('#name').addEventListener('change', (e)=>{
nameField = e.target.value;
})
// Add the new objeect instance to the array (for example: click add new object to create an object called dogs with an existingProperty of 5)
document.querySelector('#new').addEventListener('click', ()=>{
locoParentis[nameField] = new myClass();
console.log(locoParentis);
})
// Create/set new property in object instance (for example: typing 9 in the property value input sets dogs' newProperty to 9)
document.querySelector('#property').addEventListener('input', (e)=>{
locoParentis[nameField].newProperty = Number(e.target.value);
console.log(locoParentis);
})
document.querySelector('#functions').addEventListener('change', (e)=>{
// you can check here for undefined
locoParentis[nameField][e.target.value]();
console.log(locoParentis[nameField].resultProperty);
})<!DOCTYPE html>
<html>
<head>
</head>
<body>
<input id="name" placeholder="name">
<button id="new">add new object</button>
<br>
<input id="property" placeholder="property value">
<select id="functions">
<option>apply a function</option>
<option value="myFunction">sum</option>
<option value="myFunction2">multiply</option>
</select>
</body>
</html>试试这个。
但也有一些需要考虑的地方。您不需要添加单独的"添加新对象"按钮。当您选择是求和还是相乘时，可以创建一个新实例。