`compute-baseline`: Add per-release support checks to `Feature`s #1339

ddbeck · 2024-07-09T18:01:07Z

The main thing this does is gives us a way to quickly and unambiguously report true, null, or false for unqualified support relationship between a release and a feature. There's some untidiness to clean up along the way. I'll self-review with commentary.

ddbeck · 2024-07-09T18:03:10Z

packages/compute-baseline/src/baseline/support.ts

+    // TODO:
+    // let lastInitial: Release | undefined;
+    // let lastInitialBoundary: "" | "≤" | undefined;
+
+    // const reverseChronological = b.releases.slice().reverse();
+    // let previousRelease: string | undefined;
+    // for (let index = 0; index < reverseChronological.length; index++) {
+    //   const release = reverseChronological[index] as Release;
+    //   const current = feature.flatSupportedIn(release);
+
+    //   // Check if current has changed, etc.
+    // }


This is just to show where I'm going with this: walk backward through releases, then find the support-to-non-support boundary. If we stepped into a null, then that's ≤X.

ddbeck · 2024-07-09T18:03:47Z

packages/compute-baseline/src/browser-compat-data/feature.test.ts

+    describe("flatSupportedIn()", function () {
+      it("returns true for unqualified support", function () {
+        const cr = browser("chrome");
+        assert.equal(
+          feature("api.Attr").flatSupportedIn(cr.version("100")),
+          true,
+        );
+      });
+
+      it("returns false for qualified support", function () {
+        const cr = browser("chrome");
+        assert.equal(
+          feature("css.properties.line-clamp").flatSupportedIn(
+            cr.version("100"),
+          ),
+          false,
+        ); // { version_added: "…", "prefix": "-webkit-" }
+      });
+
+      it("returns false for wholly unsupported", function () {
+        const fx = browser("firefox");
+        assert.equal(
+          feature("api.Accelerometer").flatSupportedIn(fx.current()),
+          false,
+        ); // { version_added: false }
+      });
+
+      it("returns null for unknown support", function () {
+        const edge = browser("edge");
+        const f = feature("svg.elements.animate"); // { version_added: "≤79" }
+
+        assert.equal(f.flatSupportedIn(edge.version("12")), null);
+        assert.equal(f.flatSupportedIn(edge.version("79")), true);
+        assert.equal(f.flatSupportedIn(edge.version("80")), true);
+      });
+    });


This is the flat version, which ignores prefixes and partials.

ddbeck · 2024-07-09T18:04:36Z

packages/compute-baseline/src/browser-compat-data/feature.test.ts

+    describe("supportedIn()", function () {
+      it("returns support for features supported with and without qualification", function () {
+        const compat = new Compat();
+        const cr = browser("chrome");
+
+        // { version_added: "…" }
+        const bgColor = feature("css.properties.background-color").supportedIn(
+          cr.version("100"),
+        );
+        assert.equal(bgColor.length, 1);
+        assert.equal(bgColor[0]?.supported, true);
+
+        // { version_added: "…", prefix: "-webkit-" }
+        const lineClamp = feature("css.properties.line-clamp").supportedIn(
+          cr.version("100"),
+        );
+        assert.equal(lineClamp.length, 1);
+        assert.equal(lineClamp[0]?.supported, true);
+        assert.equal(lineClamp[0]?.qualifications?.prefix, "-webkit-");
+      });
+
+      it("returns mixed results for (un)prefixedfeatures", function () {
+        const fx = browser("firefox");
+        const actual = feature(
+          "css.types.image.gradient.repeating-linear-gradient",
+        ).supportedIn(fx.version("100"));
+        assert.equal(actual.length, 3); // unprefixed, -moz-, and -webkit-
+        assert(actual.some((s) => s.supported && "qualifications" in s));
+        assert(actual.some((s) => s.supported && !("qualifications" in s)));
+      });
+
+      it("returns unknown support before version ranges", function () {
+        const edge = browser("edge");
+        const f = feature("svg.elements.animate");
+        const unknown = f.supportedIn(edge.version("12"));
+        assert.equal(unknown.length, 1);
+        assert.equal(unknown[0]?.supported, null);
+
+        const known = f.supportedIn(edge.version("79"));
+        assert.equal(known.length, 1);
+        assert.equal(known[0]?.supported, true);
+      });
+    });


To find good test cases for the flat version, I ended up needing an un-flat version. We can dump this if we like, if we think we won't use it. OTOH, I did use it to write test cases. A conundrum.

Unless it gets exported to compute-baseline users, let's have it. Although if the flat version is the one we'll use most, maybe give that the nice name and rename the other one to a longer name?

Done with c07b62d.

ddbeck · 2024-07-09T18:05:15Z

packages/compute-baseline/src/browser-compat-data/feature.ts

+  rawSupportStatements(browser: Browser): SimpleSupportStatement[] {
    const support = this.data?.__compat?.support;
    if (support === undefined) {
-      throw Error("This feature contains no __compat object.");
+      throw new Error("This feature contains no __compat object.");
    }

    const statementOrStatements = support[browser.id];
-
    if (statementOrStatements === undefined) {
-      throw Error(`${this} contains no support data for ${browser.name}`);
+      throw new Error(`${this} contains no support data for ${browser.name}`);
    }

-    const rawStatements = Array.isArray(statementOrStatements)
+    return Array.isArray(statementOrStatements)
      ? statementOrStatements
      : [statementOrStatements];
+  }


This happens in a few places, so I consolidated it.

ddbeck · 2024-07-09T18:05:34Z

packages/compute-baseline/src/browser-compat-data/feature.ts

+  supportStatements(browser: Browser): SupportStatement[] {
+    return this.rawSupportStatements(browser).map((raw) =>
+      statement(raw, browser, this),
+    );
+  }


This too happens in a few places, now consolidated.

ddbeck · 2024-07-09T18:06:52Z

packages/compute-baseline/src/browser-compat-data/feature.ts

+      this.assertRealSupportStatement(s, release.browser);

-      if (!(s instanceof RealSupportStatement)) {
-        throw Error(
-          `${this.id} contains non-real values for ${browser.name}. Cannot expand support.`,
-        );


This also happens in a couple of places, so I consolidated that too—it's at the end. I have no idea how to order things. 😬

Order is hard. End is fine.

packages/compute-baseline/src/baseline/support.ts

foolip · 2024-07-09T22:17:55Z

packages/compute-baseline/src/browser-compat-data/feature.ts

+      this.assertRealSupportStatement(s, release.browser);

-      if (!(s instanceof RealSupportStatement)) {
-        throw Error(
-          `${this.id} contains non-real values for ${browser.name}. Cannot expand support.`,
-        );


Order is hard. End is fine.

packages/compute-baseline/src/browser-compat-data/feature.test.ts

foolip · 2024-07-09T22:22:29Z

packages/compute-baseline/src/browser-compat-data/feature.test.ts

+    describe("supportedIn()", function () {
+      it("returns support for features supported with and without qualification", function () {
+        const compat = new Compat();
+        const cr = browser("chrome");
+
+        // { version_added: "…" }
+        const bgColor = feature("css.properties.background-color").supportedIn(
+          cr.version("100"),
+        );
+        assert.equal(bgColor.length, 1);
+        assert.equal(bgColor[0]?.supported, true);
+
+        // { version_added: "…", prefix: "-webkit-" }
+        const lineClamp = feature("css.properties.line-clamp").supportedIn(
+          cr.version("100"),
+        );
+        assert.equal(lineClamp.length, 1);
+        assert.equal(lineClamp[0]?.supported, true);
+        assert.equal(lineClamp[0]?.qualifications?.prefix, "-webkit-");
+      });
+
+      it("returns mixed results for (un)prefixedfeatures", function () {
+        const fx = browser("firefox");
+        const actual = feature(
+          "css.types.image.gradient.repeating-linear-gradient",
+        ).supportedIn(fx.version("100"));
+        assert.equal(actual.length, 3); // unprefixed, -moz-, and -webkit-
+        assert(actual.some((s) => s.supported && "qualifications" in s));
+        assert(actual.some((s) => s.supported && !("qualifications" in s)));
+      });
+
+      it("returns unknown support before version ranges", function () {
+        const edge = browser("edge");
+        const f = feature("svg.elements.animate");
+        const unknown = f.supportedIn(edge.version("12"));
+        assert.equal(unknown.length, 1);
+        assert.equal(unknown[0]?.supported, null);
+
+        const known = f.supportedIn(edge.version("79"));
+        assert.equal(known.length, 1);
+        assert.equal(known[0]?.supported, true);
+      });
+    });


Unless it gets exported to compute-baseline users, let's have it. Although if the flat version is the one we'll use most, maybe give that the nice name and rename the other one to a longer name?

Co-authored-by: Philip Jägenstedt <philip@foolip.org>

ddbeck added 2 commits July 9, 2024 19:54

Add method to check if a release supports a feature

77259eb

Add comment illustrating next stop for this work

fef80be

ddbeck commented Jul 9, 2024

View reviewed changes

Add descriptive comments to methods, for friendly tab completion

17cd3fa

ddbeck marked this pull request as ready for review July 9, 2024 18:15

ddbeck requested a review from foolip July 9, 2024 18:15

foolip approved these changes Jul 9, 2024

View reviewed changes

ddbeck and others added 2 commits July 11, 2024 18:32

Apply suggestions from code review

c79d74c

Co-authored-by: Philip Jägenstedt <philip@foolip.org>

Use shorter name for simplified supportedIn method

c07b62d

ddbeck merged commit ca0769d into web-platform-dx:main Jul 11, 2024

ddbeck deleted the cb-exploder-part-2 branch July 11, 2024 16:34

foolip mentioned this pull request Mar 12, 2025

Increment compute-baseline version to 0.3.0 #2764

Merged

compute-baseline: Add per-release support checks to Features #1339

compute-baseline: Add per-release support checks to Features #1339

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ddbeck commented Jul 9, 2024

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`compute-baseline`: Add per-release support checks to `Feature`s #1339

`compute-baseline`: Add per-release support checks to `Feature`s #1339