用对象自己的属性初始化对象属性

Question

I get the error:

Uncaught TypeError: Cannot read property 'interval' of undefined

When I try to initialize an object like this:

var loop = {
    interval: 5 * 1000,
    maxInterval: loop.interval * 12
};

So instead I have to do it like this:

var loop = {
    interval: 5 * 1000
};
loop.maxInterval = loop.interval * 12;

Is there a better way of doing this?

Answer 1

No way.

But conceptually all you need is moving the constant one level up:

var defaultInterval = 5000;
var loop = {
    interval: defaultInterval,
    maxInterval: defaultInterval * 12
};

Answer 2

One option is using self executing function.

var loop = (function () {
    var _ = {};

    _.interval         = 5 * 1000;
    _.maxInterval      = _.interval * 12;

    return _;
})();