Closer match the loc

Author: jonathanKingston

integration-test/test-pages/runtime-checks/pages/generic-overload.html

@@ -36,9 +36,16 @@
                 localStorage.setItem('test', 'test');
                 localStorage.other = "test";
                 window.scriptyRan = true;
+                let threw = false;
+                try {
+                    localStorage.setItem('test2'); // should throw
+                } catch (e) {
+                    threw = true;
+                }
                 window.scriptOutput = {
                     item: localStorage.getItem('test'),
                     other: localStorage.getItem('other'),
+                    threw
                 }
             `)
             const scripty = document.querySelector('script#overloadedScript');
@@ -49,7 +56,8 @@
                 { name: 'node and fake node match', result: nodeAndFakeNodeMatch, expected: false },
                 { name: 'expected localStorage first response', result: window.scriptOutput, expected: {
                     item: 'test',
-                    other: 'test'
+                    other: 'test',
+                    threw: true
                 }},
                 { name: 'did not globally store', result: localStorage.getItem('test'), expected: null },
                 { name: 'did session store', result: sessionStorage.getItem('test'), expected: 'test' },
@@ -77,6 +85,12 @@
                 sessionStorage.clear();
                 sessionStorage.setItem('test', 'test');
                 sessionStorage.other = "test";
+                let threw = false;
+                try {
+                    sessionStorage.setItem('test2'); // should throw
+                } catch (e) {
+                    threw = true;
+                }
                 window.script2Output = {
                     item: sessionStorage.getItem('test'),
                     other: sessionStorage.getItem('other'),
@@ -90,7 +104,8 @@
                 { name: 'node and fake node match', result: nodeAndFakeNodeMatch, expected: false },
                 { name: 'expected localStorage first response', result: window.script2Output, expected: {
                     item: 'test',
-                    other: 'test'
+                    other: 'test',
+                    threw: true
                 }},
                 { name: 'did not globally store', result: localStorage.getItem('test'), expected: null },
                 { name: 'did session store', result: sessionStorage.getItem('test'), expected: null },

src/features/runtime-checks.js

@@ -665,22 +665,43 @@ export default class RuntimeChecks extends ContentFeature {
         class MemoryStorage {
             #data = {}
 
+            /**
+             * @param {Parameters<Storage['setItem']>[0]} id
+             * @param {Parameters<Storage['setItem']>[1]} val
+             * @returns {ReturnType<Storage['setItem']>}
+             */
             setItem (id, val) {
+                if (arguments.length < 2) throw new TypeError(`Failed to execute 'setItem' on 'Storage': 2 arguments required, but only ${arguments.length} present.`)
                 this.#data[id] = String(val)
             }
 
+            /**
+             * @param {Parameters<Storage['getItem']>[0]} id
+             * @returns {ReturnType<Storage['getItem']>}
+             */
             getItem (id) {
-                return Object.prototype.hasOwnProperty.call(this.#data, id) ? this.#data[id] : undefined
+                return Object.prototype.hasOwnProperty.call(this.#data, id) ? this.#data[id] : null
             }
 
+            /**
+             * @param {Parameters<Storage['removeItem']>[0]} id
+             * @returns {ReturnType<Storage['removeItem']>}
+             */
             removeItem (id) {
-                return delete this.#data[id]
+                delete this.#data[id]
             }
 
+            /**
+             * @returns {ReturnType<Storage['clear']>}
+             */
             clear () {
                 this.#data = {}
             }
 
+            /**
+             * @param {Parameters<Storage['key']>[0]} n
+             * @returns {ReturnType<Storage['key']>}
+             */
             key (n) {
                 const keys = Object.keys(this.#data)
                 return keys[n]