意外令牌=节点8.4中的类属性 [英] unexpected token = for class properties in node 8.4
本文介绍了意外令牌=节点8.4中的类属性的处理方法,对大家解决问题具有一定的参考价值,需要的朋友们下面随着小编来一起学习吧!
问题描述
在节点(v8.4)中运行以下代码
running the following code in node (v8.4)
class TodoStore {
todos = [];
get completedTodosCount() {
return this.todos.filter(
todo => todo.completed === true
).length;
}
report() {
if (this.todos.length === 0)
return "<none>";
return `Next todo: "${this.todos[0].task}". ` +
`Progress: ${this.completedTodosCount}/${this.todos.length}`;
}
addTodo(task) {
this.todos.push({
task: task,
completed: false,
assignee: null
});
}
}
const todoStore = new TodoStore();
todoStore.addTodo("read MobX tutorial");
console.log(todoStore.report());
todoStore.addTodo("try MobX");
console.log(todoStore.report());
todoStore.todos[0].completed = true;
console.log(todoStore.report());
todoStore.todos[1].task = "try MobX in own project";
console.log(todoStore.report());
todoStore.todos[0].task = "grok MobX tutorial";
console.log(todoStore.report());
给我以下错误:
todos = [];
^
SyntaxError: Unexpected token =
at createScript (vm.js:74:10)
at Object.runInThisContext (vm.js:116:10)
at Module._compile (module.js:537:28)
at Object.Module._extensions..js (module.js:584:10)
at Module.load (module.js:507:32)
at tryModuleLoad (module.js:470:12)
at Function.Module._load (module.js:462:3)
at Function.Module.runMain (module.js:609:10)
at startup (bootstrap_node.js:158:16)
at bootstrap_node.js:598:3
推荐答案
更新
对实例类字段的支持始于节点> = 12 。
任何版本的节点都不支持文学类属性,根据< a href = https://node.green/#ESNEXT-candidate--stage-3--instance-class-fields rel = noreferrer>此表。您仍然必须在类构造函数中设置任何实例属性:
Literal class properties are not supported by any version of node, according to this table. You'll still have to set any instance properties inside your class constructor:
class TodoStore {
constructor() {
this.todos = [];
}
// ...
}
如果希望定义一个 static
属性,您可以在声明该类之后将其直接分配给 TodoStore
引用。 :
If you wish to define a static
property, you'd assign that directly to the TodoStore
reference, after the class has been declared:
TodoStore.todos = [];
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