Improve string conversion

The previous string conversion was over-complicated, and did not match the specs in that it threw TypeErrors unnecessarily. See #129 and jsdom/jsdom#4010.

Author: asamuzaK

lib/parsers.js

@@ -96,33 +96,15 @@ const lruCache = new LRUCache({
  * Prepares a stringified value.
  *
  * @param {string|number|null|undefined} value - The value to prepare.
- * @param {object} [globalObject=globalThis] - The global object.
  * @returns {string} The prepared value.
  */
-const prepareValue = (value, globalObject = globalThis) => {
+const prepareValue = (value) => {
   // `null` is converted to an empty string.
   // @see https://webidl.spec.whatwg.org/#LegacyNullToEmptyString
   if (value === null) {
     return "";
   }
-  const type = typeof value;
-  switch (type) {
-    case "string":
-      return value.trim();
-    case "number":
-      return value.toString();
-    case "undefined":
-      return "undefined";
-    case "symbol":
-      throw new globalObject.TypeError("Can not convert symbol to string.");
-    default: {
-      const str = value.toString();
-      if (typeof str === "string") {
-        return str.trim();
-      }
-      throw new globalObject.TypeError(`Can not convert ${type} to string.`);
-    }
-  }
+  return `${value}`.trim();
 };
 
 /**
@@ -164,9 +146,7 @@ const hasCalcFunc = (val) => {
  * @returns {object} The AST or a plain object.
  */
 const parseCSS = (val, opt, toObject = false) => {
-  if (typeof val !== "string") {
-    val = prepareValue(val);
-  }
+  val = prepareValue(val);
   const ast = cssTree.parse(val, opt);
   if (toObject) {
     return cssTree.toPlainObject(ast);
@@ -183,9 +163,7 @@ const parseCSS = (val, opt, toObject = false) => {
  * @returns {boolean} True if the value is valid, false otherwise.
  */
 const isValidPropertyValue = (prop, val) => {
-  if (typeof val !== "string") {
-    val = prepareValue(val);
-  }
+  val = prepareValue(val);
   if (val === "") {
     return true;
   }
@@ -225,9 +203,7 @@ const isValidPropertyValue = (prop, val) => {
  * @returns {string|undefined} The resolved value.
  */
 const resolveCalc = (val, opt = { format: "specifiedValue" }) => {
-  if (typeof val !== "string") {
-    val = prepareValue(val);
-  }
+  val = prepareValue(val);
   if (val === "" || hasVarFunc(val) || !hasCalcFunc(val)) {
     return val;
   }
@@ -276,8 +252,8 @@ const resolveCalc = (val, opt = { format: "specifiedValue" }) => {
  * @returns {string|Array<object>|undefined} The parsed value.
  */
 const parsePropertyValue = (prop, val, opt = {}) => {
-  const { caseSensitive, globalObject, inArray } = opt;
-  val = prepareValue(val, globalObject);
+  const { caseSensitive, inArray } = opt;
+  val = prepareValue(val);
   if (val === "" || hasVarFunc(val)) {
     return val;
   } else if (hasCalcFunc(val)) {

test/CSSStyleDeclaration.test.js

@@ -1493,24 +1493,7 @@ describe("regression test for https://github.com/jsdom/cssstyle/issues/129", ()
 
   it("throws for setting Symbol", () => {
     const style = new CSSStyleDeclaration();
-    assert.throws(
-      () => style.setProperty("width", Symbol("foo")),
-      (e) => {
-        assert.strictEqual(e instanceof TypeError, true);
-        assert.strictEqual(e.message, "Can not convert symbol to string.");
-        return true;
-      }
-    );
-    assert.throws(
-      () => {
-        style.width = Symbol("foo");
-      },
-      (e) => {
-        assert.strictEqual(e instanceof TypeError, true);
-        assert.strictEqual(e.message, "Can not convert symbol to string.");
-        return true;
-      }
-    );
+    assert.throws(() => style.setProperty("width", Symbol("foo")));
   });
 });
 

test/parsers.test.js

@@ -57,63 +57,14 @@ describe("prepareValue", () => {
   it("should throw for Symbol", () => {
     const input = Symbol("foo");
 
-    assert.throws(
-      () => parsers.prepareValue(input),
-      (e) => {
-        assert.strictEqual(e instanceof globalThis.TypeError, true);
-        assert.strictEqual(e.message, "Can not convert symbol to string.");
-        return true;
-      }
-    );
+    assert.throws(() => parsers.prepareValue(input));
   });
 
-  it("should throw with window global for Symbol", () => {
-    const input = Symbol("foo");
-    const window = {
-      TypeError: globalThis.TypeError
-    };
-
-    assert.throws(
-      () => parsers.prepareValue(input, window),
-      (e) => {
-        assert.strictEqual(e instanceof window.TypeError, true);
-        assert.strictEqual(e.message, "Can not convert symbol to string.");
-        return true;
-      }
-    );
-  });
-
-  it("should throw for object.toString() not converting to string", () => {
+  it("should get string even if object.toString() not converting to string", () => {
     const input = {
       toString: () => [1]
     };
-
-    assert.throws(
-      () => parsers.prepareValue(input),
-      (e) => {
-        assert.strictEqual(e instanceof globalThis.TypeError, true);
-        assert.strictEqual(e.message, "Can not convert object to string.");
-        return true;
-      }
-    );
-  });
-
-  it("should throw for object.toString() not converting to string", () => {
-    const input = {
-      toString: () => [1]
-    };
-    const window = {
-      TypeError: globalThis.TypeError
-    };
-
-    assert.throws(
-      () => parsers.prepareValue(input, window),
-      (e) => {
-        assert.strictEqual(e instanceof window.TypeError, true);
-        assert.strictEqual(e.message, "Can not convert object to string.");
-        return true;
-      }
-    );
+    assert.throws(() => parsers.prepareValue(input));
   });
 });