Question

我需要在以下对象中使所有键（而不是值）组成一个数组，其中键以_下划线开头...

在以下代码段中，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

按如下所示替换您的getSubscriptions()

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

Object.keys（yourObject）：返回对象的键。
Array.filter（function）：基于
从数组中返回过滤后的值真实情况
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>

选择所有以下划线（_）开头的对象键

4 个答案: