Why can't document methods be held in a function?

Multi tool use
In JavaScript, you can set variables to hold certain functions and use them, like so:
var log = console.log;
log('foo');
But for some strange reason, you can't do that on most if not all document methods, such as querySelector
:
var select = document.querySelector;
// causes the error: Uncaught TypeError: Illegal invocation
select('p');
<p>...</p>
Why is that, and is there a workaround for it?
javascript function dom
add a comment |
In JavaScript, you can set variables to hold certain functions and use them, like so:
var log = console.log;
log('foo');
But for some strange reason, you can't do that on most if not all document methods, such as querySelector
:
var select = document.querySelector;
// causes the error: Uncaught TypeError: Illegal invocation
select('p');
<p>...</p>
Why is that, and is there a workaround for it?
javascript function dom
5
Because ofthis
. Try withvar select = document.querySelector.bind(document);
; stackoverflow.com/questions/2236747/…
– Federkun
Dec 31 '18 at 19:00
add a comment |
In JavaScript, you can set variables to hold certain functions and use them, like so:
var log = console.log;
log('foo');
But for some strange reason, you can't do that on most if not all document methods, such as querySelector
:
var select = document.querySelector;
// causes the error: Uncaught TypeError: Illegal invocation
select('p');
<p>...</p>
Why is that, and is there a workaround for it?
javascript function dom
In JavaScript, you can set variables to hold certain functions and use them, like so:
var log = console.log;
log('foo');
But for some strange reason, you can't do that on most if not all document methods, such as querySelector
:
var select = document.querySelector;
// causes the error: Uncaught TypeError: Illegal invocation
select('p');
<p>...</p>
Why is that, and is there a workaround for it?
var select = document.querySelector;
// causes the error: Uncaught TypeError: Illegal invocation
select('p');
<p>...</p>
var select = document.querySelector;
// causes the error: Uncaught TypeError: Illegal invocation
select('p');
<p>...</p>
javascript function dom
javascript function dom
asked Dec 31 '18 at 18:57


Eternal DarknessEternal Darkness
8331623
8331623
5
Because ofthis
. Try withvar select = document.querySelector.bind(document);
; stackoverflow.com/questions/2236747/…
– Federkun
Dec 31 '18 at 19:00
add a comment |
5
Because ofthis
. Try withvar select = document.querySelector.bind(document);
; stackoverflow.com/questions/2236747/…
– Federkun
Dec 31 '18 at 19:00
5
5
Because of
this
. Try with var select = document.querySelector.bind(document);
; stackoverflow.com/questions/2236747/…– Federkun
Dec 31 '18 at 19:00
Because of
this
. Try with var select = document.querySelector.bind(document);
; stackoverflow.com/questions/2236747/…– Federkun
Dec 31 '18 at 19:00
add a comment |
1 Answer
1
active
oldest
votes
The context seems to get lost. It's not bound with the document
. Use it this way:
var select = document.querySelector.bind(document);
// Works!
console.log(select('p'));
<p>...</p>
You can see what a function is bound to, in JavaScript: What object javascript function is bound to (what is its "this")?.
add a comment |
Your Answer
StackExchange.ifUsing("editor", function () {
StackExchange.using("externalEditor", function () {
StackExchange.using("snippets", function () {
StackExchange.snippets.init();
});
});
}, "code-snippets");
StackExchange.ready(function() {
var channelOptions = {
tags: "".split(" "),
id: "1"
};
initTagRenderer("".split(" "), "".split(" "), channelOptions);
StackExchange.using("externalEditor", function() {
// Have to fire editor after snippets, if snippets enabled
if (StackExchange.settings.snippets.snippetsEnabled) {
StackExchange.using("snippets", function() {
createEditor();
});
}
else {
createEditor();
}
});
function createEditor() {
StackExchange.prepareEditor({
heartbeatType: 'answer',
autoActivateHeartbeat: false,
convertImagesToLinks: true,
noModals: true,
showLowRepImageUploadWarning: true,
reputationToPostImages: 10,
bindNavPrevention: true,
postfix: "",
imageUploader: {
brandingHtml: "Powered by u003ca class="icon-imgur-white" href="https://imgur.com/"u003eu003c/au003e",
contentPolicyHtml: "User contributions licensed under u003ca href="https://creativecommons.org/licenses/by-sa/3.0/"u003ecc by-sa 3.0 with attribution requiredu003c/au003e u003ca href="https://stackoverflow.com/legal/content-policy"u003e(content policy)u003c/au003e",
allowUrls: true
},
onDemand: true,
discardSelector: ".discard-answer"
,immediatelyShowMarkdownHelp:true
});
}
});
Sign up or log in
StackExchange.ready(function () {
StackExchange.helpers.onClickDraftSave('#login-link');
});
Sign up using Google
Sign up using Facebook
Sign up using Email and Password
Post as a guest
Required, but never shown
StackExchange.ready(
function () {
StackExchange.openid.initPostLogin('.new-post-login', 'https%3a%2f%2fstackoverflow.com%2fquestions%2f53990598%2fwhy-cant-document-methods-be-held-in-a-function%23new-answer', 'question_page');
}
);
Post as a guest
Required, but never shown
1 Answer
1
active
oldest
votes
1 Answer
1
active
oldest
votes
active
oldest
votes
active
oldest
votes
The context seems to get lost. It's not bound with the document
. Use it this way:
var select = document.querySelector.bind(document);
// Works!
console.log(select('p'));
<p>...</p>
You can see what a function is bound to, in JavaScript: What object javascript function is bound to (what is its "this")?.
add a comment |
The context seems to get lost. It's not bound with the document
. Use it this way:
var select = document.querySelector.bind(document);
// Works!
console.log(select('p'));
<p>...</p>
You can see what a function is bound to, in JavaScript: What object javascript function is bound to (what is its "this")?.
add a comment |
The context seems to get lost. It's not bound with the document
. Use it this way:
var select = document.querySelector.bind(document);
// Works!
console.log(select('p'));
<p>...</p>
You can see what a function is bound to, in JavaScript: What object javascript function is bound to (what is its "this")?.
The context seems to get lost. It's not bound with the document
. Use it this way:
var select = document.querySelector.bind(document);
// Works!
console.log(select('p'));
<p>...</p>
You can see what a function is bound to, in JavaScript: What object javascript function is bound to (what is its "this")?.
var select = document.querySelector.bind(document);
// Works!
console.log(select('p'));
<p>...</p>
var select = document.querySelector.bind(document);
// Works!
console.log(select('p'));
<p>...</p>
answered Dec 31 '18 at 19:02
Praveen Kumar PurushothamanPraveen Kumar Purushothaman
133k23136183
133k23136183
add a comment |
add a comment |
Thanks for contributing an answer to Stack Overflow!
- Please be sure to answer the question. Provide details and share your research!
But avoid …
- Asking for help, clarification, or responding to other answers.
- Making statements based on opinion; back them up with references or personal experience.
To learn more, see our tips on writing great answers.
Sign up or log in
StackExchange.ready(function () {
StackExchange.helpers.onClickDraftSave('#login-link');
});
Sign up using Google
Sign up using Facebook
Sign up using Email and Password
Post as a guest
Required, but never shown
StackExchange.ready(
function () {
StackExchange.openid.initPostLogin('.new-post-login', 'https%3a%2f%2fstackoverflow.com%2fquestions%2f53990598%2fwhy-cant-document-methods-be-held-in-a-function%23new-answer', 'question_page');
}
);
Post as a guest
Required, but never shown
Sign up or log in
StackExchange.ready(function () {
StackExchange.helpers.onClickDraftSave('#login-link');
});
Sign up using Google
Sign up using Facebook
Sign up using Email and Password
Post as a guest
Required, but never shown
Sign up or log in
StackExchange.ready(function () {
StackExchange.helpers.onClickDraftSave('#login-link');
});
Sign up using Google
Sign up using Facebook
Sign up using Email and Password
Post as a guest
Required, but never shown
Sign up or log in
StackExchange.ready(function () {
StackExchange.helpers.onClickDraftSave('#login-link');
});
Sign up using Google
Sign up using Facebook
Sign up using Email and Password
Sign up using Google
Sign up using Facebook
Sign up using Email and Password
Post as a guest
Required, but never shown
Required, but never shown
Required, but never shown
Required, but never shown
Required, but never shown
Required, but never shown
Required, but never shown
Required, but never shown
Required, but never shown
4J93niCUdLlB0j1xPuehD0quWF1Kux3H,eOe75Hzgtjiy
5
Because of
this
. Try withvar select = document.querySelector.bind(document);
; stackoverflow.com/questions/2236747/…– Federkun
Dec 31 '18 at 19:00