选择以下划线（_）开头的所有对象键

Question

我需要在下面的对象中创建一个包含所有键（而不是值）的数组，其中键以_下划线开头...

在下面的代码片段中，我试图让getSubscriptions()返回["_foo1", "_foo2"]

 let myObj = { foo0: 'test', _foo1: 'test', _foo2: 'test', foo3: 'test', }; function getSubscriptions(obj, cb) { // should return ["_foo1", "_foo2"] let ret = ["foo1", "_foo2"]; return cb(ret); } getSubscriptions(myObj, (ret) => { if (match(ret, ["_foo1", "_foo2"]) ) { $('.nope').hide(); return $('.works').show(); } $('.nope').show(); $('.works').hide(); }); function match(arr1, arr2) { if(arr1.length !== arr2.length) { return false; } for(var i = arr1.length; i--;) { if(arr1[i] !== arr2[i]) { return false;} } return true; } 

 body { background: #333; color: #4ac388; padding: 2em; font-family: monospace; font-size: 19px; } .nope { color: #ce4242; } .container div{ padding: 1em; border: 3px dotted; } 

 <script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script> <div class="container"> <div class="works">It Works!</div> <div class="nope"> Doesn't Work...</div> </div> 

Answer 1

您可以使用Object.keys和Array.filter

 let myObj = { foo0: 'test', _foo1: 'test', _foo2: 'test', foo3: 'test', }; let result = Object.keys(myObj).filter(v => v.startsWith("_")); console.log(result); 

Answer 2

将Object.keys与filter一起使用，并检查第一个字符是否为下划线_ ：

 let myObj = { foo0: 'test', _foo1: 'test', _foo2: 'test', foo3: 'test', }; const res = Object.keys(myObj).filter(([c]) => c == "_"); console.log(res); 

Answer 3

替换你的getSubscriptions()如下

 function getSubscriptions(obj, cb) {
        let ret = Object.keys(myObj).filter(ele => ele.startsWith('_'))
        return cb(ret)
    }

• Object.keys（yourObject）：返回yourobject的键。

• Array.filter（function）：根据数组返回过滤后的值
  真实的情况

• String.startsWith：如果传递的字符串以（'_'）开头，则返回true或false

Answer 4

在过滤器中尝试.startsWith("_") 。

 let myObj = { foo0: 'test', _foo1: 'test', _foo2: 'test', foo3: 'test', }; function getSubscriptions(obj, cb) { // should return ["_foo1", "_foo2"] let ret = Object.keys(myObj).filter(v => v.startsWith("_")); return cb(ret); } getSubscriptions(myObj, (ret) => { if (match(ret, ["_foo1", "_foo2"]) ) { $('.nope').hide(); $('.works').show(); } // $('.nope').show(); // you have misplaced these 2 lines //$('.works').hide(); }); function match(arr1, arr2) { if(arr1.length !== arr2.length) { return false; } for(var i = arr1.length; i--;) { if(arr1[i] !== arr2[i]) { return false;} } return true; } 

 body { background: #333; color: #4ac388; padding: 2em; font-family: monospace; font-size: 19px; } .nope { color: #ce4242; } .container div{ padding: 1em; border: 3px dotted; } 

 <script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script> <div class="container"> <div class="works">It Works!</div> <div class="nope"> Doesn't Work...</div> </div>