Javascript 无法从事件处理程序访问js对象方法
这个HTML片段创建一个对象原型,实例化它,然后尝试从事件中使用该对象的方法,但未成功Javascript 无法从事件处理程序访问js对象方法,javascript,html,object,eventhandler,Javascript,Html,Object,Eventhandler,这个HTML片段创建一个对象原型,实例化它,然后尝试从事件中使用该对象的方法,但未成功 <body> <button type="button" onclick="TestLogic()">Test Logic</button> <script> function onOff() //Object prototype { this.state = false;
<body>
<button type="button" onclick="TestLogic()">Test Logic</button>
<script>
function onOff() //Object prototype
{
this.state = false;
function setState(newState) {
this.state = newState;
}
}
var inputOne = new onOff(); //Instantiate object prototype
function TestLogic() //buttonClick Event Handler
{
inputOne.setState(true);
// generates Uncaught Type Error undefined is not a function */
document.inputOne.setState(true);
// generates Uncaught Type Error Cannot read property setState of undefined
}
</script>
</body>
onOff中的函数是私有的,它不是作为公共属性发布的。将函数setStatenewState{…}更改为this.setState=functionnewState{…}。您对javascript上下文有误解。MDN对此很有好处。请参阅评论以了解错误所在:
<body>
<button type="button" onclick="TestLogic()">Test Logic</button>
<script>
function onOff() //Object prototype
{
this.state = false;
//set method to context of creating Object
this.setState = function (newState) {
this.state = newState;
}
}
var inputOne = new onOff(); //Instantiate object prototype
function TestLogic() //buttonClick Event Handler
{
inputOne.setState(true);
//document is not a scope, window is global scope
window.inputOne.setState(true);
}
</script>
</body>
试试这个
<html>
<body>
<button type="button" onclick="TestLogic()">Test Logic</button>
<script>
function onOff() //Object prototype
{
this.state = false;
this.setState=function(newState)
{
this.state = newState;
console.log(this.state);
}
}
var inputOne = new onOff();
function TestLogic()
{
inputOne.setState(true);
}
</script>
</body>
</html>
如果你想使用原型,那么就使用这样的原型
function Object () {
this.instanceMethod = false;
}
Object.prototype.prototypeMethod = function () {};
另外,您应该避免使用内联事件侦听器,而是这样做
document.querySelector('button').addEventListener('click', function () {
// logic
});
这里有一个例子,所有这些都一起使用
document.inputOne应该只是inputOne,函数setState应该是this.setState=函数setstatetstate是onOff的本地值。你永远不会让外界呼叫你。inputOne也不是文档对象的属性。我建议阅读,以更好地了解JavaScript及其在浏览器中的工作原理。由于OP似乎是初学者,解释他们的代码有什么问题以及您的解决方案如何/为什么解决这些问题对他们来说非常有价值。因为OP似乎是初学者,解释他们的代码出了什么问题,以及您的解决方案解决问题的方式/原因对他们来说非常有价值。
<body>
<button type="button">Test Logic 1</button>
<button type="button">Test Logic 2</button>
<button type="button">Test Logic 3</button>
<script>
//Object prototype
function OnOff(element) {
this.element = element;
this.state = false;
}
OnOff.prototype.setState = function (newState) {
this.state = newState;
if (this.state) {
this.element.style.backgroundColor = 'red';
} else {
this.element.style.backgroundColor = 'grey';
}
};
// bind to elements
var elements = document.querySelectorAll('button');
for (var i = 0; i < elements.length; i++) {
elements[i].addEventListener('click', function () {
if (!this.onOff) this.onOff = new OnOff(this);
this.onOff.setState(!this.onOff.state);
});
}
</script>
</body>