[英]How to instruct Closure Compiler not to rename/remove a local variable?
In the following code, I need the variable some_var
not to be renamed or removed by Google's Closure Compiler. 在以下代码中,我不需要Google的Closure Compiler重命名或删除变量
some_var
。
function scopedEval(code){
var some_var = 'world' ;
return eval('('+code+')') ;
}
scopedEval('alert("hello, "+some_var)') ;
The code to be eval-ed relies on the existence of a few variables, so I need them to be left untouched. 要评估的代码依赖于一些变量的存在,因此我需要保持不变。
How can I instruct Closure Compiler to do that? 如何指示Closure Compiler执行此操作?
PS: PS:
Please disregard the issue about the use of eval
being a bad practice. 请忽略有关使用
eval
是一种不良做法的问题。 That's another matter entirely. 这完全是另一回事。
There might be some Closure Compiler options allowing this sort of thing specifically, but failing that, I would tackle the problem one of these two ways: 可能会有一些Closure Compiler选项专门允许这种事情,但是如果失败,我将通过以下两种方法之一解决问题:
Create a global object to store your variables, and then use the js_externs
option to prevent it from being munged: 创建一个全局对象来存储您的变量,然后使用
js_externs
选项防止它被蒙住:
// ==ClosureCompiler==
// @compilation_level ADVANCED_OPTIMIZATIONS
// @output_file_name default.js
// @js_externs vars
// ==/ClosureCompiler==
vars = {};
Then you can apply string properties to this object that should be left untouched 然后,您可以将字符串属性应用于该对象,该属性应保持不变
function scopedEval(code){
vars['some_var'] = 'world';
return eval('('+code+')');
}
scopedEval('alert("hello, "+vars["some_var"])');
If for some reason vars['some_var']
won't work for you and you need to use some_var
literally inside the eval
ed code, then you can use with
to get around this. 如果由于某种原因
vars['some_var']
对您不起作用,而您需要在eval
代码中直接使用some_var
,则可以使用with
来解决此问题。 In this case, you don't need to declare vars
as an extern. 在这种情况下,您无需将
vars
声明为extern。
function scopedEval(code){
var vars = {
"some_var": "world"
};
with(vars) {
return eval('('+code+')');
}
}
scopedEval('alert("hello, "+some_var)');
I'll leave it up to your discretion whether or not you feel dirty using the two features of JavaScript that attract the most vitriol together, namely with
and eval
. 无论您使用JavaScript的两个吸引最多硫酸的功能(
with
和eval
是否感到脏,我都会自行决定。
One option is to use the function constructor: 一种选择是使用函数构造函数:
var scopedEval = new Function(
"code",
"var some_var = 'world'; return eval('('+code+')');");
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