Skip to content
New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Check if startsWith is configurable #702

Closed
wants to merge 1 commit into from
Closed

Check if startsWith is configurable #702

Changes from all commits
Commits
Show all changes
1 commit
Select commit
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
28 changes: 15 additions & 13 deletions packages/core-js/modules/es.string.starts-with.js
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -8,16 +8,18 @@ var correctIsRegExpLogic = require('../internals/correct-is-regexp-logic');
var nativeStartsWith = ''.startsWith;
var min = Math.min;

// `String.prototype.startsWith` method
// https://tc39.github.io/ecma262/#sec-string.prototype.startswith
$({ target: 'String', proto: true, forced: !correctIsRegExpLogic('startsWith') }, {
startsWith: function startsWith(searchString /* , position = 0 */) {
var that = String(requireObjectCoercible(this));
notARegExp(searchString);
var index = toLength(min(arguments.length > 1 ? arguments[1] : undefined, that.length));
var search = String(searchString);
return nativeStartsWith
? nativeStartsWith.call(that, search, index)
: that.slice(index, index + search.length) === search;
}
});
if(Object.getOwnPropertyDescriptor(String.prototype, "startsWith").configurable) {
Copy link
Author

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

If the property is not configurable, do nothing since it is going to fail anyway with an exception

Copy link
Contributor

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

When would it not be configurable?

// `String.prototype.startsWith` method
// https://tc39.github.io/ecma262/#sec-string.prototype.startswith
$({ target: 'String', proto: true, forced: !correctIsRegExpLogic('startsWith') }, {
startsWith: function startsWith(searchString /* , position = 0 */) {
var that = String(requireObjectCoercible(this));
notARegExp(searchString);
var index = toLength(min(arguments.length > 1 ? arguments[1] : undefined, that.length));
var search = String(searchString);
return nativeStartsWith
? nativeStartsWith.call(that, search, index)
: that.slice(index, index + search.length) === search;
}
});
}