function foo(){
function bar() {
return 3;
}
return bar();
function bar() {
return 8;
}
}
alert(foo());
题 2:
function foo(){
var bar = function() {
return 3;
};
return bar();
var bar = function() {
return 8;
};
}
alert(foo());
题 3:
alert(foo());
function foo(){
var bar = function() {
return 3;
};
return bar();
var bar = function() {
return 8;
};
}
题 4:
function foo(){
return bar();
var bar = function() {
return 3;
};
var bar = function() {
return 8;
};
}
alert(foo());
答案是8、3、3和 [Type Error: bar is not a function]
分析：
//**Simulated processing sequence for Question 1**
function foo(){
//define bar once
function bar() {
return 3;
}
//redefine it
function bar() {
return 8;
}
//return its invocation
return bar(); //8
}
alert(foo());
return 语句后面的代码是运行不到的啊……
//**Simulated processing sequence for Question 2**
function foo(){
//a declaration for each function expression
var bar = undefined;
var bar = undefined;
//first Function Expression is executed
bar = function() {
return 3;
};
// Function created by first Function Expression is invoked
return bar();
// second Function Expression unreachable
}
alert(foo()); //3
//**Simulated processing sequence for Question 4**
function foo(){
//a declaration for each function expression
var bar = undefined;
var bar = undefined;
return bar(); //TypeError: "bar not defined"
//neither Function Expression is reached
}
alert(foo());