LibJS: Add JSON.parse

Author: https://github.com/mattco98
Commit: b155e64b67
Pull-request: https://github.com/SerenityOS/serenity/pull/2545
Reviewed-by: https://github.com/Dexesttp
Reviewed-by: https://github.com/awesomekling

Libraries/LibJS/Tests/JSON.parse.js

@@ -0,0 +1,43 @@
+load("test-common.js");
+
+try {
+    assert(JSON.parse.length === 2);
+
+    const properties = [
+        ["5", 5],
+        ["null", null],
+        ["true", true],
+        ["false", false],
+        ['"test"', "test"],
+        ['[1,2,"foo"]', [1, 2, "foo"]],
+        ['{"foo":1,"bar":"baz"}', { foo: 1, bar: "baz" }],
+    ];
+
+    properties.forEach(testCase => {
+        assertDeepEquals(JSON.parse(testCase[0]), testCase[1]);
+    });
+
+    let syntaxErrors = [
+        undefined,
+        NaN,
+        -NaN,
+        Infinity,
+        -Infinity,
+        '{ "foo" }',
+        '{ foo: "bar" }',
+        "[1,2,3,]",
+        "[1,2,3, ]",
+        '{ "foo": "bar",}',
+        '{ "foo": "bar", }',
+    ];
+
+    syntaxErrors.forEach(error => assertThrowsError(() => {
+        JSON.parse(error);
+    }, {
+        error: SyntaxError,
+    }));
+
+    console.log("PASS");
+} catch (e) {
+    console.log("FAIL: " + e);
+}