JSLint:意外的赋值表达式 [英] JSLint: Unexpected assignment expression

问题描述

我收到此警告:

Unexpected assignment expression.
return task.completed = true; // Line 63, Pos 39

使用此代码时:

completeAll: function () {
    this.tasks = this.tasks.filter(function (task) {
        return task.completed = true;
    });
}

为什么?而且我还能怎么写这个表达式来避免JSLint抛出警告?

Why? And how else could I write this expression to avoid JSLint throwing warnings?

P.S.

该代码块来自此处的Vue TodoMVC示例: http://todomvc.dev/examples/vue/，因此我认为必须已经进行了代码审查.

The codeblock is taken from the Vue TodoMVC Example here: http://todomvc.dev/examples/vue/, therefore I assume that code review must have already been happened.

推荐答案

之所以这样做，是因为警告您在不只是上下文中使用=而不是==或===分配，但还要对分配的结果做些事情.那是完全有效的JavaScript，但是经常是无意的.一个更好的例子是:

It's doing that because it's warning you that you're using = rather than == or === in a context where you're not just assigning, but also doing something with the assigned result. That's perfectly valid JavaScript, but it's frequently unintentional. A better example is:

if (foo = bar) {
    // ...
}

...您可能指的是==或===(检查它们是否相等).

...where you probably meant == or === (checking that they were equal).

如何修复它取决于您要执行的操作.从方法的名称来看，我认为您正在尝试设置task.completed，在这种情况下，坦率地说filter是使用错误的函数.他们应该使用forEach:

How you fix it depends on what you're trying to do. From the name of the method, I assume you're (well, they're) trying to set task.completed, in which case frankly filter is the wrong function to use; they should be using forEach:

completeAll: function () {
    this.tasks.forEach(function (task) {
        task.completed = true;
    });
}

但是如果您(他们)真的想使用filter:

but if you (they) really wanted to use filter:

completeAll: function () {
    this.tasks = this.tasks.filter(function (task) {
        task.completed = true;
        return true; // Or return task.completed
    });
}

如果您要进行比较(我对此表示怀疑)，而不是进行分配，那么:

If you're trying to do a comparison (which I doubt), not an assignment, then:

return task.completed == true;

或

return !!task.completed;

或

return task.completed; // If you know it's boolean already

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