Javascript 如何在循环内创建动态变量名？

How do I create dynamic variable names inside a loop?

提问by Philipp Bergmann

I'm working on an ajax google maps script and I need to create dynamic variable names in a for loop.

我正在处理 ajax 谷歌地图脚本，我需要在 for 循环中创建动态变量名称。

for (var i = 0; i < coords.length; ++i) {
    var marker+i = "some stuff";
}

What I want to get is: marker0, marker1, marker2and so on. and I guess there is something wrong with marker+i

我想得到的是：marker0, marker1,marker2等等。我想有什么问题marker+i

Firebug gives me this: missing ; before statement

Firebug 给了我这个： missing ; before statement

回答by JohnP

Use an array for this.

为此使用数组。

var markers = [];
for (var i = 0; i < coords.length; ++i) {
    markers[i] = "some stuff";
}

回答by Todd Ditchendorf

I agree it is generally preferable to use an Arrayfor this.

我同意通常最好为此使用 an Array。

However, this can also be accomplished in JavaScript by simply adding properties to the current scope (the global scope, if top-level code; the function scope, if within a function) by simply using this– which always refers to the current scope.

然而，这也可以在 JavaScript 中通过简单地通过简单地使用– 始终指代当前范围，通过简单地将属性添加到当前范围（全局范围，如果是顶级代码；函数范围，如果在函数内）this来实现。

for (var i = 0; i < coords.length; ++i) {
? ? this["marker"+i] = "some stuff";
}

You can later retrieve the stored values (if you are within the same scope as when they were set):

您可以稍后检索存储的值（如果您在设置它们时的范围内）：

var foo = this.marker0;
console.log(foo); // "some stuff"

This slightly odd feature of JavaScript is rarely used (with good reason), but in certain situations it can be useful.

JavaScript 的这个有点奇怪的特性很少使用（有充分的理由），但在某些情况下它可能很有用。

回答by Safiq

Try this

尝试这个

window['marker'+i] = "some stuff"; 

回答by kayleeFrye_onDeck

In regards to iterative variable names, I like making dynamic variables using Template literals. Every Tom, Dick, and Harry uses the array-style, which is fine. Until you're working with arrays anddynamic variables, oh boy! Eye-bleed overload. Since Template literals have limited support right now, eval()is even another option.

关于迭代变量名，我喜欢使用模板文字制作动态变量。每个 Tom、Dick 和 Harry 都使用数组样式，这很好。在您使用数组和动态变量之前，天哪！眼出血过载。由于模板文字现在支持有限，eval()因此甚至是另一种选择。

v0 = "Variable Naught";
v1 = "Variable One";

for(i = 0; i < 2; i++)
{//console.log(i) equivalent is console.log(`${i}`)
  dyV = eval(`v${i}`);
  console.log(`v${i}`); /* => v0;   v1;  */      
  console.log(dyV);  /* => Variable Naught; Variable One;  */
}

When I was hacking my way through the APIs I made this little looping snippet to see behavior depending on what was done with the Template literals compared to say, Ruby. I liked Ruby's behavior more; needing to use eval()to get the value is kind of lame when you're used to getting it automatically.

当我通过 API 破解我的方式时，我制作了这个小循环片段来查看行为，这取决于与 Ruby 相比，模板文字所做的事情。我更喜欢Ruby的行为；需要使用eval()获得的价值是一种跛脚的，当你使用自动得到它。

_0 = "My first variable"; //Primitive
_1 = {"key_0":"value_0"}; //Object
_2 = [{"key":"value"}]    //Array of Object(s)


for (i = 0; i < 3; i++)
{
  console.log(`_${i}`);           /*  var
                                   * =>   _0  _1  _2  */

  console.log(`"_${i}"`);         /*  var name in string  
                                   * => "_0"  "_1"  "_2"  */

  console.log(`_${i}` + `_${i}`); /*  concat var with var
                                   * => _0_0  _1_1  _2_2  */

  console.log(eval(`_${i}`));     /*  eval(var)
                                   * => My first variable
                                        Object {key_0: "value_0"}
                                        [Object]  */
}

回答by Md Junaid Alam

You can use eval() method to declare dynamic variables. But better to use an Array.

您可以使用 eval() 方法来声明动态变量。但最好使用数组。

for (var i = 0; i < coords.length; ++i) {
    var str ="marker"+ i+" = undefined";
    eval(str);
}

回答by vikram prajapat

var marker  = [];
for ( var i = 0; i < 6; i++) {               
     marker[i]='Hello'+i;                    
}
console.log(marker);
alert(marker);

回答by Alfgaar

 var marker+i = "some stuff";

coudl be interpreted like this: create a variable named marker (undefined); then add to i; then try to assign a value to to the result of an expression, not possible. What firebug is saying is this: var marker; i = 'some stuff'; this is what firebug expects a comma after marker and before i; var is a statement and don't (apparently) accepts expressions. Not so good an explanation but i hope it helps.

可以这样解释：创建一个名为标记（未定义）的变量；然后加到我；然后尝试为表达式的结果赋值，不可能。firebug 的意思是： var 标记；i = '一些东西'; 这就是萤火虫期望在标记之后和 i 之前有一个逗号；var 是一个语句，不（显然）接受表达式。不是很好的解释，但我希望它有所帮助。