Question

This question already has answers here:

How do I make JavaScript Object using a variable String to define the class name? (12 answers)

Using a variable value to call an array element (7 answers)

Closed 9 years ago.

难于解释。我基本上想做以下工作:

var doWhat = "speak";

var speak = {
    hello: function() { alert: "Hello!"; }
};

// Won t work
doWhat.hello();

It s a bad example, but you should be able to get what I mean. Is it possible somehow ?

Answer 1

You can use eval(doWhat).hello();. That way the contents of doWhat will be evaluated to the object reference.

Answer 2

你可以做这样的事情。

var doWhat = {}, str = "speak";

doWhat[str] = {
    hello : function() {}
}; 

doWhat[str].hello();

Answer 3

jsName =  PageIndexController ;

//ST1
eval("if( typeof jsName ===  undefined )alert(111);");

//ST1
eval("if( typeof " + jsName + " ===  undefined )alert(222);");

//ST1 not work
//ST2 work and the output: 222;

//there are two different way using eval, we will get 2 different outcome.

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