I know I should not submit a question with this title, but I am really confused by the following code. anyone can explain why the last line print 1?
enviroment: chrome 80.0.3987.163
console.log(foo) // undefined if (true) { foo = 1 console.log(foo) // 1 function foo() { console.log("a") } console.log(foo) // 1, function foo is hoist foo = 2 console.log(foo) // 2 } else { function foo() { console.log("b") } } console.log(foo) // 1, why?
if remove the function declaration, it's OK.
console.log(foo) // undefined if (true) { foo = 1 console.log(foo) // 1 foo = 2 console.log(foo) // 2 } else { function foo() { console.log("b") } } console.log(foo) // 2
Well, after the function declaration inside the if block, the JS engine thinks that you're referring to the function. If you change the function name it should work properly.
console.log(foo) // undefined
if (true) {
var foo = 1;
console.log(foo, 'foo1') // 1
function foo2() {
console.log("a")
}
console.log(foo, 'still foo1') // 1, function foo is hoist
foo = 2
console.log(foo, 'foo2') // 2
} else {
function foo() {
console.log("b")
}
}
console.log(foo) // 1, why?
This first foo is the global scope
after the function with the same name, it was identified as a local scope ie it become a local scope within that function but if you change the function name everything should work normal ie foo will now be of value 2
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