在JavaScript关联数组中动态创建键

Question

如何在javascript关联数组中动态创建键？

到目前为止,我发现的所有文档都是更新已创建的密钥:

 arr['key'] = val;

我有这样的字符串 " name = oscar "

我想最终得到这样的东西:

{ name: 'whatever' }

那就是我拆分字符串并获取第一个元素,我想把它放在字典中.

码

var text = ' name = oscar '
var dict = new Array();
var keyValuePair = text.split(' = ');
dict[ keyValuePair[0] ] = 'whatever';
alert( dict ); // prints nothing.

Answer 1

不知何故,所有示例虽然运作良好,但过于复杂:

• 他们使用new Array(),这是一个简单的关联数组(AKA字典)的过度杀伤(和开销).
• 更好的用途new Object().工作正常,但为什么所有这些额外打字？

这个问题被标记为"初学者",所以让我们简单一点.

在JavaScript中使用字典或"为什么JavaScript没有特殊的字典对象？"的超级简单方法:

// create an empty associative array (in JavaScript it is called ... Object)
var dict = {};   // huh? {} is a shortcut for "new Object()"

// add a key named fred with value 42
dict.fred = 42;  // we can do that because "fred" is a constant
                 // and conforms to id rules

// add a key named 2bob2 with value "twins!"
dict["2bob2"] = "twins!";  // we use the subscript notation because
                           // the key is arbitrary (not id)

// add an arbitrary dynamic key with a dynamic value
var key = ..., // insanely complex calculations for the key
    val = ...; // insanely complex calculations for the value
dict[key] = val;

// read value of "fred"
val = dict.fred;

// read value of 2bob2
val = dict["2bob2"];

// read value of our cool secret key
val = dict[key];

现在让我们改变价值观:

// change the value of fred
dict.fred = "astra";
// the assignment creates and/or replaces key-value pairs

// change value of 2bob2
dict["2bob2"] = [1, 2, 3];  // any legal value can be used

// change value of our secret key
dict[key] = undefined;
// contrary to popular beliefs assigning "undefined" does not remove the key

// go over all keys and values in our dictionary
for (key in dict) {
  // for-in loop goes over all properties including inherited properties
  // let's use only our own properties
  if (dict.hasOwnProperty(key)) {
    console.log("key = " + key + ", value = " + dict[key]);
  }
}

删除值也很容易:

// let's delete fred
delete dict.fred;
// fred is removed, the rest is still intact

// let's delete 2bob2
delete dict["2bob2"];

// let's delete our secret key
delete dict[key];

// now dict is empty

// let's replace it, recreating all original data
dict = {
  fred:    42,
  "2bob2": "twins!"
  // we can't add the original secret key because it was dynamic,
  // we can only add static keys
  // ...
  // oh well
  temp1:   val
};
// let's rename temp1 into our secret key:
if (key != "temp1") {
  dict[key] = dict.temp1; // copy the value
  delete dict.temp1;      // kill the old key
} else {
  // do nothing, we are good ;-)
}

Answer 2

使用第一个示例.如果该密钥不存在,则将添加该密钥.

var a = new Array();
a['name'] = 'oscar';
alert(a['name']);

将弹出一个包含'oscar'的消息框.

尝试:

var text = 'name = oscar'
var dict = new Array()
var keyValuePair = text.replace(/ /g,'').split('=');
dict[ keyValuePair[0] ] = keyValuePair[1];
alert( dict[keyValuePair[0]] );

Answer 3

Javascript 没有关联数组,它有对象.

以下代码行完全相同 - 将对象上的'name'字段设置为'orion'.

var f = new Object(); f.name = 'orion';
var f = new Object(); f['name'] = 'orion';
var f = new Array(); f.name = 'orion';
var f = new Array(); f['name'] = 'orion';
var f = new XMLHttpRequest(); f['name'] = 'orion';

看起来你有一个关联数组,因为Array它也是一个Object- 但是你实际上并没有在数组中添加东西,而是在对象上设置字段.

现在已经解决了这个问题,这是一个有效的解决方案

var text = '{ name = oscar }'
var dict = new Object();

// Remove {} and spaces
var cleaned = text.replace(/[{} ]/g, '');

// split into key and value
var kvp = cleaned.split('=');

// put in the object
dict[ kvp[0] ] = kvp[1];
alert( dict.name ); // prints oscar.

Answer 4

响应MK_Dev,可以迭代,但不能连续.(显然需要一个数组)

快速谷歌搜索在javascript中显示哈希表

用于循环散列中的值的示例代码(来自上述链接):

var myArray = new Array();
myArray['one'] = 1;
myArray['two'] = 2;
myArray['three'] = 3;

// show the values stored
for (var i in myArray) {
    alert('key is: ' + i + ', value is: ' + myArray[i]);
}

Answer 5

原始代码（我添加了行号，因此可以参考它们）：

1  var text = ' name = oscar '
2  var dict = new Array();
3  var keyValuePair = text.split(' = ');
4  dict[ keyValuePair[0] ] = 'whatever';
5  alert( dict ); // Prints nothing.

差不多好了...

• 第 1 行：您应该trim对文本进行处理，因此它是name = oscar.

• 第 3 行：好的，只要你的等号周围总是有空格。最好不要trim在第 1 行。使用=和修剪每个 keyValuePair

• 在 3 之后和 4 之前添加一行：

    key = keyValuePair[0];`
  

• 第 4 行：现在变成：

    dict[key] = keyValuePair[1];
  

• 第 5 行：更改为：

    alert( dict['name'] );  // It will print out 'oscar'
  

我想说这dict[keyValuePair[0]]行不通。您需要设置一个字符串keyValuePair[0]并将其用作关联键。这是我让我的工作的唯一途径。设置完成后，您可以使用数字索引或键入引号来引用它。