Variable not being set [duplicate]

问题

This question already has an answer here:

Closed 7 years ago.

Possible Duplicate:
Return Global Variable from Javascript Method

I have this.

var thisData = "";
function calculateThings(newData) {
     thisData = newData.things.otherthings //has a value of 10;
}
alert(thisData) //returns nothing

What am I doing wrong?

回答1:

you need to call your function:

calculateThings(newData);

should be more like:

 var thisData = "";
 function calculateThings(data) {
      thisData = data.things.otherthings //has a value of 10;
 }
 calculateThings(newData);
 alert(thisData) //returns nothing

where data is your parameter, and you can pass whatever you want into it.

回答2:

You created a function but never call it. You need to call it via:

var thisData = "";
function calculateThings(newData) {
     thisData = newData.things.otherthings //has a value of 10;
}
alert(calculateThings(thisData)); 

or you can self-invoke the function like:

(function calculateThings(newData) {
     thisData = newData.things.otherthings //has a value of 10;
})()

来源：https://stackoverflow.com/questions/12427059/variable-not-being-set