Check if Javascript boolean is set?

This question already has an answer here:

How do I check if an object has a property in JavaScript? 22 answers

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如果没有设置值，那意味着它是undefined 。

function printStuff(params) {
  if (params.hello !== undefined) {
    console.log(params.hello);
  } else {
    console.log('Hello, ');
  }
}

printStuff({ });
printStuff({
  hello: 'World'
});

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If you want to check whether an object has a specific property, that's the in keyword:

'required' in params

There's also the hasOwnProperty method, if you need to exclude properties inherited from a prototype (you probably don't for this case):

params.hasOwnProperty('required')

---

这会解决你的问题吗？

if(required!=undefined)

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