weird variable hoisting in javascript

Question

so we know that variables declared with the var keyword are hoisted and if we try to access their value before they have been initialized we get undefined. However, In the code below logging the name variable logs the function and not undefined why ?

console.log(name);
console.log(lol);

var name = function(args = "Hello World"){
    console.log(args)
}

var lol = function(args = "Hello world") {
    console.log(args)
}

the output is

function(args = "Hello World"){
    console.log(args)
}

and

main.js:57 undefined

why isnt name variable undefined ?

Ralph Ritoch · Accepted Answer · 2020-05-31 09:27:37Z

2

The window which is the root scope already has a name property. Try the following and look at the output in your console. If you click the link the page that opens has MyWin as the output for name.

HTML (test.html)

<head>
    <title>test</title>
</head>

<body>
    <a href="test.html" target="MyWin">Click me!</a>
    <script src="test.js"></script>
</body>

</html>

Javascript (test.js)

console.log("name", name);
console.log("notname", notname);
console.log("lol", lol);


var notname = function (args = "Hello World") {
    console.log(args)
}

var lol = function (args = "Hello world") {
    console.log(args)
}

answered May 31, 2020 at 9:27

Ralph Ritoch

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Comments

codeandcloud · Accepted Answer · 2020-05-31 09:11:54Z

0

Consider the code

console.log(test);

var test = function(args = "Hello World"){
    console.log(args)
}

This will return undefined because only declarations are hoisted. That is, your code after hoisting will be

var test;
console.log(test);

test = function(args = "Hello World"){
    console.log(args)
}

answered May 31, 2020 at 9:11

codeandcloud

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2 Comments

Karambit Over a year ago

i know about this. What i dont understand is why name is not undefined.

Karambit Over a year ago

copy the html from pastebin.com/JbL89E6m and open it in your browser to see this

Himanshu Pandey · Accepted Answer · 2020-05-31 09:16:38Z

0

I think you should logging like that why you confused.

console.log(name);
console.log(lol);

var name = function(args = "Hello World"){
    console.log(args)
}

var lol = function(args = "Hello world") {
    console.log(args)
}

console.log(name);
console.log(lol);

answered May 31, 2020 at 9:16

Himanshu Pandey

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1 Comment

Karambit Over a year ago

copy the html from pastebin.com/JbL89E6m and open it in your browser to see this

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