如何在一个可以被其他函数（JavaScript）访问的函数中定义全局变量？

Question

The user is passing a value to a function and I'm trying to assign that value to a global variable but can't figure out how to do it.

var a;    

function changeValue(newValue)    {
     a = newValue;
}

alert("Value of 'a' outside the function " + a); //I want this to output the value of newValue

Answer 1

Your function works fine, you simply need to call it:

var a;    

function changeValue(newValue)    {
     a = newValue;
}

changeValue(100); // Function call changes the value of a to 100

alert("Value of 'a' outside the function " + a); // 100

Answer 2

Here you are:

var a;
b = 0;

function changeValue(newValue) {
    a = newValue;
    b = newValue;
}
changeValue('a');
changeValue('b');
alert("Value of 'a' outside the function " + a);
alert("Value of 'b' outside the function " + b);

Hope this help.