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Gathering detailed insights and metrics for resize-observer-polyfill

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Gathering detailed insights and metrics for resize-observer-polyfill

resize-observer-polyfill - 1.5.1 | npmpackage.info

resize-observer-polyfill

A polyfill for the Resize Observer API

1.5.1

1,758

MIT

JavaScript

1.9

Installations

npm install resize-observer-polyfill

Developer Guide

BETA

Typescript

Yes

Module System

CommonJS

Node Version

11.0.0

NPM Version

6.4.1 Pull Requests

Open

25

Total

39

Closed

10

Merged

4

Issues

Open

32

Total

64

Closed

32

Releases

v1.5.1

1.5.1

Updated on Dec 09, 2018

v1.5.0

1.5.0

Updated on Nov 16, 2017

v1.4.2

1.4.2

Updated on Apr 03, 2017

v1.4.1

1.4.1

Updated on Feb 17, 2017

v1.4.0

1.4.0

Updated on Feb 16, 2017

Remove redundant/empty ResizeObserver class

1.3.2

Updated on Dec 18, 2016

View All 18 releases

Languages

JavaScript

JavaScript (100%)

Developer

que-etc

Download Statistics

Total Downloads

Last Day

Last Week

Last Month

Last Year

GitHub Statistics

MIT License

1,758 Stars

99 Commits

132 Forks

12 Watchers

17 Branches

4 Contributors

Updated on Jun 19, 2025

Maintainers

View All 4 Contributors

Package Meta Information

Latest Version

1.5.1

Package Id

resize-observer-polyfill@1.5.1

Size

31.97 kB

NPM Version

6.4.1

Node Version

11.0.0

Published on

Dec 09, 2018

Total Downloads

Cumulative downloads

Total Downloads

NaN

Last Day

NaN

Compared to previous day

Last Week

NaN

Compared to previous week

Last Month

NaN

Compared to previous month

Last Year

NaN

Compared to previous year

Weekly Downloads

Monthly Downloads

Yearly Downloads

Dev Dependencies

babel-eslint cpy-cli eslint jasmine jasmine-core karma karma-chrome-launcher karma-firefox-launcher karma-jasmine karma-jasmine-html-reporter karma-rollup-preprocessor karma-sauce-launcher karma-sourcemap-loader karma-spec-reporter promise-polyfill rollup rollup-plugin-typescript typescript

ResizeObserver Polyfill

A polyfill for the Resize Observer API.

Implementation is based on the MutationObserver and uses Mutation Events as a fall back if the first one is not supported, so there will be no polling unless DOM changes. Doesn't modify observed elements. Handles CSS transitions/animations and can possibly observe changes caused by dynamic CSS pseudo-classes, e.g. by :hover.

Follows the spec and the native implementation. The size is 2.44 KiB when minified and gzipped.

Live demo (has style problems in IE10 and lower).

Installation

From NPM:

1npm install resize-observer-polyfill --save-dev

~~From Bower:~~ (will be removed with the next major release)

1bower install resize-observer-polyfill --save-dev

Browser Support

Polyfill has been tested in the following browsers:

NOTE: Internet Explorer 8 and its earlier versions are not supported.

Usage Example

It's recommended to use this library in the form of a ponyfill, which doesn't inflict modifications of the global object.

1import ResizeObserver from 'resize-observer-polyfill';
2
3const ro = new ResizeObserver((entries, observer) => {
4    for (const entry of entries) {
5        const {left, top, width, height} = entry.contentRect;
6
7        console.log('Element:', entry.target);
8        console.log(`Element's size: ${ width }px x ${ height }px`);
9        console.log(`Element's paddings: ${ top }px ; ${ left }px`);
10    }
11});
12
13ro.observe(document.body);

Package's main file is a ES5 UMD bundle that will be swapped with the ES6 modules version for those bundlers that are aware of the module field, e.g. for Rollup or webpack 2+.

Note: global version of the polyfill (dist/ResizeObserver.global) is deprecated and will be removed in the next major release.

Observation Strategy

As mentioned above, this implementation primarily (but not solely) relies on Mutation Observer with a fallback to Mutation Events for IE 9 and IE 10.

Speaking of Mutation Events as a fallback approach: they might not be as ugly as they are being rendered, particularly when their calls are batched, throttled and there is no need to analyze changes. Given that, they won't interrupt browser's reflow/repaint cycles (same for MutationObserver) and may even outperform Internet Explorer's implementation of MO causing little to no performance degradation. In contemporary browsers (Chrome, Firefox, etc.) Mutation Observer slows down the suite that includes 200 iterations of adding/removing elements, changing attributes and modifying text data by less than 1%. Internet Explorer gives different results with MO slowing down the same suite by 2-3% while Mutation Events show the difference of ~0.6%.

As for the reasons why other approaches, namely the iframe/object and scroll strategies, were ruled out:

They require the observed element to be non-statically positioned.
You can't apply them directly to quite a number of elements: <img>, <input>, <textarea>, <canvas>, <tr>, <tbody>, <thead>, <table>, etc. For most of them you would need to keep an extra <div> wrapper and almost all instances of the SVGGraphicsElement will be out of scope.
The ResizeObserver spec requires to deliver notifications when a non-empty visible element becomes hidden, i.e. when either this element directly or one of its parent nodes receive the display: none state. Same goes for when it's being removed from or added to the DOM. It's not possible to handle these cases merely by using former approaches, so you'd still need to either subscribe for DOM mutations or to continuously check the element's state.

And though every approach has its own limitations, I reckon that it'd be too much of a trade-off to have those constraints when building a polyfill.

Limitations

Notifications are delivered ~20ms after actual changes happen.
Changes caused by dynamic pseudo-classes, e.g. :hover and :focus, are not tracked. As a workaround you could add a short transition which would trigger the transitionend event when an element receives one of the former classes (example).
Delayed transitions will receive only one notification with the latest dimensions of an element.

Building and Testing

To build polyfill. Creates UMD bundle in the dist folder:

1npm run build

To run a code style test:

1npm run test:lint

Running unit tests:

1npm run test:spec

To test in a browser that is not present in karma's config file:

1npm run test:spec:custom

Testing against a native implementation:

1npm run test:spec:native

NOTE: after you invoke spec:native and spec:custom commands head to the http://localhost:9876/debug.html page.

No vulnerabilities found.

10

Binary-Artifacts

Determines if the project has generated executable (binary) artifacts in the source repository.

10

License

Determines if the project has defined a license.

1

Code-Review

Determines if the project requires human code review before pull requests (aka merge requests) are merged.

0

Maintained

Determines if the project is "actively maintained".

0

CII-Best-Practices

Determines if the project has an OpenSSF (formerly CII) Best Practices Badge.

0

Security-Policy

Determines if the project has published a security policy.

0

Fuzzing

Determines if the project uses fuzzing.

0

Branch-Protection

Determines if the default and release branches are protected with GitHub's branch protection settings.

0

SAST

Determines if the project uses static code analysis.

0

Vulnerabilities

Determines if the project has open, known unfixed vulnerabilities.

Reason

72 existing vulnerabilities detected

Details

Warn: Project is vulnerable to: GHSA-67hx-6x53-jw92
Warn: Project is vulnerable to: GHSA-6chw-6frg-f759
Warn: Project is vulnerable to: GHSA-v88g-cgmw-v5xw
Warn: Project is vulnerable to: GHSA-93q8-gq69-wqmw
Warn: Project is vulnerable to: GHSA-fwr7-v2mv-hh25
Warn: Project is vulnerable to: GHSA-pp7h-53gx-mx7r
Warn: Project is vulnerable to: GHSA-qwcr-r2fm-qrc7
Warn: Project is vulnerable to: GHSA-v6h2-p8h4-qcjw
Warn: Project is vulnerable to: GHSA-cwfw-4gq5-mrqx
Warn: Project is vulnerable to: GHSA-g95f-p29q-9xw4
Warn: Project is vulnerable to: GHSA-grv7-fg5c-xmjg
Warn: Project is vulnerable to: GHSA-c6rq-rjc2-86v2
Warn: Project is vulnerable to: GHSA-pxg6-pf52-xh8x
Warn: Project is vulnerable to: GHSA-3xgq-45jj-v275
Warn: Project is vulnerable to: GHSA-gxpj-cx7g-858c
Warn: Project is vulnerable to: GHSA-w573-4hg7-7wgq
Warn: Project is vulnerable to: GHSA-j4f2-536g-r55m
Warn: Project is vulnerable to: GHSA-r7qp-cfhv-p84w
Warn: Project is vulnerable to: GHSA-3gx7-xhv7-5mx3
Warn: Project is vulnerable to: GHSA-74fj-2j2h-c42q
Warn: Project is vulnerable to: GHSA-pw2r-vq6v-hr8c
Warn: Project is vulnerable to: GHSA-jchw-25xp-jwwc
Warn: Project is vulnerable to: GHSA-cxjh-pqwp-8mfp
Warn: Project is vulnerable to: GHSA-8r6j-v8pm-fqw3
Warn: Project is vulnerable to: MAL-2023-462
Warn: Project is vulnerable to: GHSA-43f8-2h32-f4cj
Warn: Project is vulnerable to: GHSA-6x33-pw7p-hmpq
Warn: Project is vulnerable to: GHSA-pc5p-h8pf-mvwp
Warn: Project is vulnerable to: GHSA-qqgx-2p2h-9c37
Warn: Project is vulnerable to: GHSA-2pr6-76vf-7546
Warn: Project is vulnerable to: GHSA-8j8c-7jfh-h6hx
Warn: Project is vulnerable to: GHSA-896r-f27r-55mw
Warn: Project is vulnerable to: GHSA-7x7c-qm48-pq9c
Warn: Project is vulnerable to: GHSA-rc3x-jf5g-xvc5
Warn: Project is vulnerable to: GHSA-6c8f-qphg-qjgp
Warn: Project is vulnerable to: GHSA-jf85-cpcp-j695
Warn: Project is vulnerable to: GHSA-p6mc-m468-83gw
Warn: Project is vulnerable to: GHSA-29mw-wpgm-hmr9
Warn: Project is vulnerable to: GHSA-35jh-r3h4-6jhm
Warn: Project is vulnerable to: GHSA-82v2-mx6x-wq7q
Warn: Project is vulnerable to: GHSA-952p-6rrq-rcjv
Warn: Project is vulnerable to: GHSA-f8q6-p94x-37v3
Warn: Project is vulnerable to: GHSA-vh95-rmgr-6w4m
Warn: Project is vulnerable to: GHSA-xvch-5gv4-984h
Warn: Project is vulnerable to: GHSA-fhjf-83wg-r2j9
Warn: Project is vulnerable to: GHSA-6fx8-h7jm-663j
Warn: Project is vulnerable to: GHSA-hj48-42vr-x3v9
Warn: Project is vulnerable to: GHSA-hrpp-h998-j3pp
Warn: Project is vulnerable to: GHSA-p8p7-x288-28g6
Warn: Project is vulnerable to: GHSA-gcx4-mw62-g8wm
Warn: Project is vulnerable to: GHSA-c2qf-rxjj-qqgw
Warn: Project is vulnerable to: GHSA-4g88-fppr-53pp
Warn: Project is vulnerable to: GHSA-4jqc-8m5r-9rpr
Warn: Project is vulnerable to: GHSA-fxwf-4rqh-v8g3
Warn: Project is vulnerable to: GHSA-25hc-qcg6-38wj
Warn: Project is vulnerable to: GHSA-xfhh-g9f5-x4m4
Warn: Project is vulnerable to: GHSA-qm95-pgcg-qqfq
Warn: Project is vulnerable to: GHSA-cqmj-92xf-r6r9
Warn: Project is vulnerable to: GHSA-j44m-qm6p-hp7m
Warn: Project is vulnerable to: GHSA-3jfq-g458-7qm9
Warn: Project is vulnerable to: GHSA-r628-mhmh-qjhw
Warn: Project is vulnerable to: GHSA-9r2w-394v-53qc
Warn: Project is vulnerable to: GHSA-5955-9wpr-37jh
Warn: Project is vulnerable to: GHSA-qq89-hq3f-393p
Warn: Project is vulnerable to: GHSA-f5x3-32g6-xq36
Warn: Project is vulnerable to: GHSA-72xf-g2v4-qvf3
Warn: Project is vulnerable to: GHSA-7p7h-4mm5-852v
Warn: Project is vulnerable to: GHSA-mgfv-m47x-4wqp
Warn: Project is vulnerable to: GHSA-3h5v-q93c-6h6q
Warn: Project is vulnerable to: GHSA-72mh-269x-7mh5
Warn: Project is vulnerable to: GHSA-h4j5-c7cj-74xg
Warn: Project is vulnerable to: GHSA-p9pc-299p-vxgp

Score

1.9

/10

Last Scanned on 2025-07-07

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