Error in callback for watcher "source": "TypeError: Cannot read properties of undefined (reading 'apply')"
时间: 2023-11-04 20:49:33 浏览: 46
引用中的错误信息"Error in callback for watcher 'source': TypeError: Cannot read properties of undefined (reading 'apply')"表示在监视属性"source"的回调函数中出现了错误,错误类型是"TypeError",具体错误原因是无法读取undefined的属性"apply"。这通常是因为回调函数未定义引起的粗心错误。
要解决这个问题,你需要确保在监视属性的回调函数中定义了正确的函数名,并且正确地引用了属性值。请检查你的代码中的监视属性的回调函数是否正确定义,并确保函数名拼写无误。在你的代码中,应该类似于以下形式:
watch: {
source: {
handler(newvalue) {
// 在这里处理回调函数的逻辑
}
}
}
请注意,handler函数名首字母应该小写,并且确保正确引用了属性值。通过这样的更改,你应该能够解决这个错误。
相关问题
Error in callback for watcher "inventoryList": "TypeError: Cannot read properties of undefined (reading 'apply')"
这个错误提示的意思是在监视属性"inventoryList"的回调函数中发生了一个错误,具体是"TypeError: Cannot read properties of undefined (reading 'apply')"。这个错误通常是由于在定义监视器时未正确设置回调函数引起的。解决这个问题的方法是确保正确定义监视器的回调函数,并确保函数名没有拼写错误。您可以检查一下代码中与"inventoryList"相关的监视器的回调函数是否正确设置,以及是否存在拼写错误。<span class="em">1</span><span class="em">2</span><span class="em">3</span>
#### 引用[.reference_title]
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[ .reference_list ]
Error in callback for watcher "echartData": "TypeError: Cannot read properties of undefined (reading 'length')"
以下是关于"Error in callback for watcher 'echartData': 'TypeError: Cannot read properties of undefined (reading 'length')'"的解释和演示:
1. 对象属性检查
```javascript
var b = {name:1}
console.log(b.hasOwnProperty('name')) // 输出:true
```
2. Promise执行顺序
```javascript
const p1 = new Promise((resolve, reject) => {
setTimeout(() => {
resolve(1)
throw new Error('p1失败信息')
}, 2000)
})
const p2 = p1
.then((val) => {
console.log(val, 'p2成功返回的')
return val + 1
})
.catch((err) => {
console.log(err, 'p2失败返回的')
return err
})
Promise.all([p2, Promise.reject(3)])
.then((val2) => {
console.log(val2, 'all成功返回的')
})
.catch((err2) => {
console.log(err2, 'all失败返回的')
})
```