IE11-CSS変数のポリフィル/スクリプトは存在しますか？

Question

混合Webブラウザー環境（Chrome/IE11）でWebページを開発しています。 IE11はCSS変数をサポートしていません。IE11でCSS変数を使用できるようにするポリフィルまたはスクリプトが存在しますか？

Answer 1

はい、ルートレベルのカスタムプロパティ（IE9 +）を処理している限り。

• GitHub： https://github.com/jhildenbiddle/css-vars-ponyfill
• NPM： https://www.npmjs.com/package/css-vars-ponyfill
• デモ： https://codepen.io/jhildenbiddle/pen/ZxYJrR

READMEから：

機能

• CSSカスタムプロパティの静的な値へのクライアント側の変換
• 最新のブラウザーと従来のブラウザーの両方でのランタイム値のライブ更新
• <link>、<style>、および@import CSSの変換
• 相対url()パスを絶対URLに変換します
• 連鎖およびネストされたvar()関数をサポート
• var()関数のフォールバック値をサポート
• Webコンポーネント/シャドウDOM CSSをサポート
• <link>および<style>の変更の監視モード自動更新
• UMDおよびES6モジュールが利用可能
• 含まれるTypeScript定義
• 軽量（6k min + gzip）および依存関係なし

制限事項

• カスタムプロパティのサポートは：root宣言に限定されます
• Var（）の使用はプロパティ値に制限されています（ W3C仕様 ごと）

ライブラリが処理できる内容の例をいくつか示します。

ルートレベルのカスタムプロパティ

:root {
    --a: red;
}

p {
    color: var(--a);
}

連鎖カスタムプロパティ

:root {
    --a: var(--b);
    --b: var(--c);
    --c: red;
}

p {
    color: var(--a);
}

ネストされたカスタムプロパティ

:root {
    --a: 1em;
    --b: 2;
}

p {
    font-size: calc(var(--a) * var(--b));
}

フォールバック値

p {
    font-size: var(--a, 1rem);
    color: var(--b, var(--c, var(--d, red))); 
}

変換<link>、<style>、および@import CSS

<link rel="stylesheet" href="/absolute/path/to/style.css">
<link rel="stylesheet" href="../relative/path/to/style.css">

<style>
    @import "/absolute/path/to/style.css";
    @import "../relative/path/to/style.css";
</style>

Webコンポーネント/シャドウDOMを変換します

<custom-element>
  #shadow-root
    <style>
      .my-custom-element {
        color: var(--test-color);
      }
    </style>
    <div class="my-custom-element">Hello.</div>
</custom-element>

完全を期すために： w3c specs

お役に立てれば。

（恥知らずな自己宣伝：チェック）

Answer 2

[I has kode]による上記の質問コメントセクションのコードペンスニペットリンクの+1。 IE11が文句を言わないように、関数宣言をJSON形式で定義するには、スニペットを少し修正する必要があることがわかりました。以下は、コードペンスニペットのわずかに変更されたバージョンです。

let cssVarPoly = {
    init: function() {
        // first lets see if the browser supports CSS variables
        // No version of IE supports window.CSS.supports, so if that isn't supported in the first place we know CSS variables is not supported
        // Edge supports supports, so check for actual variable support
        if (window.CSS && window.CSS.supports && window.CSS.supports('(--foo: red)')) {
            // this browser does support variables, abort
            console.log('your browser supports CSS variables, aborting and letting the native support handle things.');
            return;
        } else {
            // Edge barfs on console statements if the console is not open... lame!
            console.log('no support for you! polyfill all (some of) the things!!');
            document.querySelector('body').classList.add('cssvars-polyfilled');
        }

        cssVarPoly.ratifiedVars = {};
        cssVarPoly.varsByBlock = {};
        cssVarPoly.oldCSS = {};

        // start things off
        cssVarPoly.findCSS();
        cssVarPoly.updateCSS();
    },

    // find all the css blocks, save off the content, and look for variables
    findCSS: function() {
        let styleBlocks = document.querySelectorAll('style:not(.inserted),link[type="text/css"]');

        // we need to track the order of the style/link elements when we save off the CSS, set a counter
        let counter = 1;

        // loop through all CSS blocks looking for CSS variables being set
        [].forEach.call(styleBlocks, function (block) {
            // console.log(block.nodeName);
            let theCSS;
            if (block.nodeName === 'STYLE') {
                // console.log("style");
                theCSS = block.innerHTML;
                cssVarPoly.findSetters(theCSS, counter);
            } else if (block.nodeName === 'LINK') {
                // console.log("link");
                cssVarPoly.getLink(block.getAttribute('href'), counter, function (counter, request) {
                    cssVarPoly.findSetters(request.responseText, counter);
                    cssVarPoly.oldCSS[counter] = request.responseText;
                    cssVarPoly.updateCSS();
                });
                theCSS = '';
            }
            // save off the CSS to parse through again later. the value may be empty for links that are waiting for their ajax return, but this will maintain the order
            cssVarPoly.oldCSS[counter] = theCSS;
            counter++;
        });
    },

    // find all the "--variable: value" matches in a provided block of CSS and add them to the master list
    findSetters: function(theCSS, counter) {
        // console.log(theCSS);
        cssVarPoly.varsByBlock[counter] = theCSS.match(/(--.+:.+;)/g) || [];
    },

    // run through all the CSS blocks to update the variables and then inject on the page
    updateCSS: function() {
        // first lets loop through all the variables to make sure later vars trump earlier vars
        cssVarPoly.ratifySetters(cssVarPoly.varsByBlock);

        // loop through the css blocks (styles and links)
        for (let curCSSID in cssVarPoly.oldCSS) {
            // console.log("curCSS:",oldCSS[curCSSID]);
            let newCSS = cssVarPoly.replaceGetters(cssVarPoly.oldCSS[curCSSID], cssVarPoly.ratifiedVars);
            // put it back into the page
            // first check to see if this block exists already
            if (document.querySelector('#inserted' + curCSSID)) {
                // console.log("updating")
                document.querySelector('#inserted' + curCSSID).innerHTML = newCSS;
            } else {
                // console.log("adding");
                var style = document.createElement('style');
                style.type = 'text/css';
                style.innerHTML = newCSS;
                style.classList.add('inserted');
                style.id = 'inserted' + curCSSID;
                document.getElementsByTagName('head')[0].appendChild(style);
            }
        };
    },

    // parse a provided block of CSS looking for a provided list of variables and replace the --var-name with the correct value
    replaceGetters: function(curCSS, varList) {
        // console.log(varList);
        for (let theVar in varList) {
            // console.log(theVar);
            // match the variable with the actual variable name
            let getterRegex = new RegExp('var\\(\\s*' + theVar + '\\s*\\)', 'g');
            // console.log(getterRegex);
            // console.log(curCSS);
            curCSS = curCSS.replace(getterRegex, varList[theVar]);

            // now check for any getters that are left that have fallbacks
            let getterRegex2 = new RegExp('var\\(\\s*.+\\s*,\\s*(.+)\\)', 'g');
            // console.log(getterRegex);
            // console.log(curCSS);
            let matches = curCSS.match(getterRegex2);
            if (matches) {
                // console.log("matches",matches);
                matches.forEach(function (match) {
                    // console.log(match.match(/var\(.+,\s*(.+)\)/))
                    // find the fallback within the getter
                    curCSS = curCSS.replace(match, match.match(/var\(.+,\s*(.+)\)/)[1]);
                });

            }

            // curCSS = curCSS.replace(getterRegex2,varList[theVar]);
        };
        // console.log(curCSS);
        return curCSS;
    },

    // determine the css variable name value pair and track the latest
    ratifySetters: function(varList) {
        // console.log("varList:",varList);
        // loop through each block in order, to maintain order specificity
        for (let curBlock in varList) {
            let curVars = varList[curBlock];
            // console.log("curVars:",curVars);
            // loop through each var in the block
            curVars.forEach(function (theVar) {
                // console.log(theVar);
                // split on the name value pair separator
                let matches = theVar.split(/:\s*/);
                // console.log(matches);
                // put it in an object based on the varName. Each time we do this it will override a previous use and so will always have the last set be the winner
                // 0 = the name, 1 = the value, strip off the ; if it is there
                cssVarPoly.ratifiedVars[matches[0]] = matches[1].replace(/;/, '');
            });
        };
        // console.log(ratifiedVars);
    },

    // get the CSS file (same domain for now)
    getLink: function(url, counter, success) {
        var request = new XMLHttpRequest();
        request.open('GET', url, true);
        request.overrideMimeType('text/css;');
        request.onload = function () {
            if (request.status >= 200 && request.status < 400) {
                // Success!
                // console.log(request.responseText);
                if (typeof success === 'function') {
                    success(counter, request);
                }
            } else {
                // We reached our target server, but it returned an error
                console.warn('an error was returned from:', url);
            }
        };

        request.onerror = function () {
            // There was a connection error of some sort
            console.warn('we could not get anything from:', url);
        };

        request.send();
    }

};

cssVarPoly.init();

Answer 3

このポリフィルにより、IE11のカスタムプロパティをほぼ完全にサポートできます。
https://github.com/nuxodin/ie11CustomProperties

使い方

このスクリプトは、IEが最小限のカスタムプロパティをサポートし、カスケードを念頭に置いてプロパティを定義および読み出すことができるという事実を利用しています。
.myEl {-ie-test:'aaa'} // only one dash allowed! "-"
次に、JavaScriptでそれを読みます
getComputedStyle( querySelector('.myEl') )['-ie-test']

READMEの機能：

• 動的に追加されたhtmlコンテンツを処理します
• 動的に追加される<style>、<link>要素を処理します
• チェーン--bar:var(--foo)
• フォールバックvar(--color, blue)
• ：focus、：target、：hover
• js-integration：
  • style.setProperty('--x','y')
  • style.getPropertyValue('--x')
  • getComputedStyle(el).getPropertyValue('--inherited')
• インラインスタイル：<div ie-style="--color:blue"...
• カスケード作品
• 相続作品
• 3k（min + gzip）未満で、依存関係なし

デモ：

https://rawcdn.githack.com/nuxodin/ie11CustomProperties/b851ec2b6b8e336a78857b570d9c12a8526c9a91/test.html

Answer 4

このバージョンのPolyfillを試しましたが、CSSの1行に複数の変数（FIフォントと色）があるとエラーになりました。私の同僚が助けてくれました。行94を参照してください。

let cssVarPoly = {
    init: function() {
        // first lets see if the browser supports CSS variables
        // No version of IE supports window.CSS.supports, so if that isn't supported in the first place we know CSS variables is not supported
        // Edge supports supports, so check for actual variable support
        if (window.CSS && window.CSS.supports && window.CSS.supports('(--foo: red)')) {
            // this browser does support variables, abort
            // console.log('your browser supports CSS variables, aborting and letting the native support handle things.');
            return;
        } else {
            // Edge barfs on console statements if the console is not open... lame!
            // console.log('no support for you! polyfill all (some of) the things!!');
            document.querySelector('body').classList.add('cssvars-polyfilled');
        }

        cssVarPoly.ratifiedVars = {};
        cssVarPoly.varsByBlock = {};
        cssVarPoly.oldCSS = {};

        // start things off
        cssVarPoly.findCSS();
        cssVarPoly.updateCSS();
    },

    // find all the css blocks, save off the content, and look for variables
    findCSS: function() {
        let styleBlocks = document.querySelectorAll('style:not(.inserted),link[type="text/css"]');

        // we need to track the order of the style/link elements when we save off the CSS, set a counter
        let counter = 1;

        // loop through all CSS blocks looking for CSS variables being set
        [].forEach.call(styleBlocks, function (block) {
            // console.log(block.nodeName);
            let theCSS;
            if (block.nodeName === 'STYLE') {
                // console.log("style");
                theCSS = block.innerHTML;
                cssVarPoly.findSetters(theCSS, counter);
            } else if (block.nodeName === 'LINK') {
                // console.log("link");
                cssVarPoly.getLink(block.getAttribute('href'), counter, function (counter, request) {
                    cssVarPoly.findSetters(request.responseText, counter);
                    cssVarPoly.oldCSS[counter] = request.responseText;
                    cssVarPoly.updateCSS();
                });
                theCSS = '';
            }
            // save off the CSS to parse through again later. the value may be empty for links that are waiting for their ajax return, but this will maintain the order
            cssVarPoly.oldCSS[counter] = theCSS;
            counter++;
        });
    },

    // find all the "--variable: value" matches in a provided block of CSS and add them to the master list
    findSetters: function(theCSS, counter) {
        // console.log(theCSS);
        cssVarPoly.varsByBlock[counter] = theCSS.match(/(--.+:.+;)/g) || [];
    },

    // run through all the CSS blocks to update the variables and then inject on the page
    updateCSS: function() {
        // first lets loop through all the variables to make sure later vars trump earlier vars
        cssVarPoly.ratifySetters(cssVarPoly.varsByBlock);

        // loop through the css blocks (styles and links)
        for (let curCSSID in cssVarPoly.oldCSS) {
            // console.log("curCSS:",oldCSS[curCSSID]);
            let newCSS = cssVarPoly.replaceGetters(cssVarPoly.oldCSS[curCSSID], cssVarPoly.ratifiedVars);
            // put it back into the page
            // first check to see if this block exists already
            if (document.querySelector('#inserted' + curCSSID)) {
                // console.log("updating")
                document.querySelector('#inserted' + curCSSID).innerHTML = newCSS;
            } else {
                // console.log("adding");
                var style = document.createElement('style');
                style.type = 'text/css';
                style.innerHTML = newCSS;
                style.classList.add('inserted');
                style.id = 'inserted' + curCSSID;
                document.getElementsByTagName('head')[0].appendChild(style);
            }
        };
    },

    // parse a provided block of CSS looking for a provided list of variables and replace the --var-name with the correct value
    replaceGetters: function(curCSS, varList) {
        // console.log(varList);
        for (let theVar in varList) {
            // console.log(theVar);
            // match the variable with the actual variable name
            // console.log (theVar);
            var res = theVar.match(/--[a-zA-Z0-9-]+/g);
            // console.log (res[0]);
            theVar = res[0];
            let getterRegex = new RegExp('var\\(\\s*' + theVar + '\\s*\\)', 'g');
            // console.log(getterRegex);
            // console.log(curCSS);
            curCSS = curCSS.replace(getterRegex, varList[theVar]);

            // now check for any getters that are left that have fallbacks
            let getterRegex2 = new RegExp('var\\(\\s*.+\\s*,\\s*(.+)\\)', 'g');
            // console.log(getterRegex);
            // console.log(curCSS);
            let matches = curCSS.match(getterRegex2);
            if (matches) {
                // console.log("matches",matches);
                matches.forEach(function (match) {
                    // console.log(match.match(/var\(.+,\s*(.+)\)/))
                    // find the fallback within the getter
                    curCSS = curCSS.replace(match, match.match(/var\(.+,\s*(.+)\)/)[1]);
                });
            }

            // curCSS = curCSS.replace(getterRegex2,varList[theVar]);
        };
        // console.log(curCSS);
        return curCSS;
    },

    // determine the css variable name value pair and track the latest
    ratifySetters: function(varList) {
        // console.log("varList:",varList);
        // loop through each block in order, to maintain order specificity
        for (let curBlock in varList) {
            let curVars = varList[curBlock];
            // console.log("curVars:",curVars);
            // loop through each var in the block
            curVars.forEach(function (theVar) {
                // console.log(theVar);
                // split on the name value pair separator
                let matches = theVar.split(/:\s*/);
                // console.log(matches);
                // put it in an object based on the varName. Each time we do this it will override a previous use and so will always have the last set be the winner
                // 0 = the name, 1 = the value, strip off the ; if it is there
                cssVarPoly.ratifiedVars[matches[0]] = matches[1].replace(/;/, '');
            });
        };
        // console.log(ratifiedVars);
    },

    // get the CSS file (same domain for now)
    getLink: function(url, counter, success) {
        var request = new XMLHttpRequest();
        request.open('GET', url, true);
        request.overrideMimeType('text/css;');
        request.onload = function () {
            if (request.status >= 200 && request.status < 400) {
                // Success!
                // console.log(request.responseText);
                if (typeof success === 'function') {
                    success(counter, request);
                }
            } else {
                // We reached our target server, but it returned an error
                console.warn('an error was returned from:', url);
            }
        };

        request.onerror = function () {
            // There was a connection error of some sort
            console.warn('we could not get anything from:', url);
        };

        request.send();
    }

};

cssVarPoly.init();