javascript ES6 类：脚本中出现意外标记？
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ES6 Classes: Unexpected token in script?
提问by panthro
I'm copying an example trying to learn ES6 but i'm getting a compile error:
我正在复制一个尝试学习 ES6 的示例，但出现编译错误：
Unexpected token (2:5)
It appears to be referring to the count = 0;
它似乎指的是count = 0;
What am I doing wrong?
我究竟做错了什么？
class Counter {
count = 0;
constructor() {
setInterval(function() {
this.tick();
}.bind(this), 1000);
}
tick() {
this.count ++;
console.log(this.count);
}
}
回答by nils
In ES2015, when using the classsyntax, you need to define instance variables either in the constructor or one of the methods (there is a proposal for the next iteration, ES2016, to allow for your syntax: ES Class Fields & Static Properties)
在 ES2015 中，使用class语法时，您需要在构造函数或其中一个方法中定义实例变量（下一次迭代 ES2016 有一个建议，以允许您的语法：ES Class Fields & Static Properties）
class Counter {
constructor() {
this.count = 0;
setInterval(function() {
this.tick();
}.bind(this), 1000);
}
tick() {
this.count++;
console.log(this.count);
}
}
var c = new Counter();
Check out the fiddle:
看看小提琴：
回答by imprfekt
Perhaps it's the compiler issue. Check what version of Babel you're using.
In my case I missed the babel-preset-stage-0dependency.
可能是编译器的问题。检查您使用的 Babel 版本。
就我而言，我错过了babel-preset-stage-0依赖项。
回答by Riley Green
3 years late so you probably figured it out, but I placed the count variable in the constructor
晚了 3 年，所以你可能想通了，但我将 count 变量放在构造函数中
class Counter {
constructor(count = 0) {
this.count = count
setInterval(function() {
this.tick();
}.bind(this), 1000);
}
tick() {
this.count ++;
console.log(this.count);
}
}
let counter = new Counter;
counter.tick()
gave it more control by calling the tick function
通过调用tick函数给它更多的控制
class Counter {
constructor(count = 0) {
this.count = count;
}
tick() {
let count = this.count;
setInterval(function() {
console.log(count++);
}, 1000);
}
}
let counter = new Counter;
// counter.tick()
