diff --git a/js/package-lock.json b/js/package-lock.json
index 0fca515b61238..23557a9bba9ff 100644
--- a/js/package-lock.json
+++ b/js/package-lock.json
@@ -17,6 +17,7 @@
         "@types/npmlog": "^4.1.4",
         "@typescript-eslint/eslint-plugin": "^8.46.2",
         "@typescript-eslint/parser": "^8.46.2",
+        "baseline-browser-mapping": "^2.9.13",
         "dir-compare": "^4.2.0",
         "esbuild": "^0.25.0",
         "esbuild-plugin-polyfill-node": "^0.3.0",
@@ -1624,9 +1625,9 @@
       ]
     },
     "node_modules/baseline-browser-mapping": {
-      "version": "2.8.20",
-      "resolved": "https://registry.npmjs.org/baseline-browser-mapping/-/baseline-browser-mapping-2.8.20.tgz",
-      "integrity": "sha512-JMWsdF+O8Orq3EMukbUN1QfbLK9mX2CkUmQBcW2T0s8OmdAUL5LLM/6wFwSrqXzlXB13yhyK9gTKS1rIizOduQ==",
+      "version": "2.9.13",
+      "resolved": "https://registry.npmjs.org/baseline-browser-mapping/-/baseline-browser-mapping-2.9.13.tgz",
+      "integrity": "sha512-WhtvB2NG2wjr04+h77sg3klAIwrgOqnjS49GGudnUPGFFgg7G17y7Qecqp+2Dr5kUDxNRBca0SK7cG8JwzkWDQ==",
       "dev": true,
       "license": "Apache-2.0",
       "bin": {
@@ -6969,9 +6970,9 @@
       "dev": true
     },
     "baseline-browser-mapping": {
-      "version": "2.8.20",
-      "resolved": "https://registry.npmjs.org/baseline-browser-mapping/-/baseline-browser-mapping-2.8.20.tgz",
-      "integrity": "sha512-JMWsdF+O8Orq3EMukbUN1QfbLK9mX2CkUmQBcW2T0s8OmdAUL5LLM/6wFwSrqXzlXB13yhyK9gTKS1rIizOduQ==",
+      "version": "2.9.13",
+      "resolved": "https://registry.npmjs.org/baseline-browser-mapping/-/baseline-browser-mapping-2.9.13.tgz",
+      "integrity": "sha512-WhtvB2NG2wjr04+h77sg3klAIwrgOqnjS49GGudnUPGFFgg7G17y7Qecqp+2Dr5kUDxNRBca0SK7cG8JwzkWDQ==",
       "dev": true
     },
     "binary-extensions": {
diff --git a/js/package.json b/js/package.json
index cb8b09f4247a6..18cd765dff85a 100644
--- a/js/package.json
+++ b/js/package.json
@@ -10,6 +10,7 @@
     "@types/npmlog": "^4.1.4",
     "@typescript-eslint/eslint-plugin": "^8.46.2",
     "@typescript-eslint/parser": "^8.46.2",
+    "baseline-browser-mapping": "^2.9.13",
     "dir-compare": "^4.2.0",
     "esbuild": "^0.25.0",
     "esbuild-plugin-polyfill-node": "^0.3.0",
diff --git a/js/web/lib/wasm/jsep/backend-webgpu.ts b/js/web/lib/wasm/jsep/backend-webgpu.ts
index e486e4b0e043d..41d3f72872b30 100644
--- a/js/web/lib/wasm/jsep/backend-webgpu.ts
+++ b/js/web/lib/wasm/jsep/backend-webgpu.ts
@@ -247,7 +247,7 @@ export class WebGpuBackend {
     const requireFeatureIfAvailable = (feature: GPUFeatureName) =>
       adapter.features.has(feature) && requiredFeatures.push(feature) && true;
     // Try chromium-experimental-timestamp-query-inside-passes and fallback to timestamp-query
-    if (!requireFeatureIfAvailable('chromium-experimental-timestamp-query-inside-passes' as GPUFeatureName)) {
+    if (!requireFeatureIfAvailable('chromium-experimental-timestamp-query-inside-passes')) {
       requireFeatureIfAvailable('timestamp-query');
     }
     requireFeatureIfAvailable('shader-f16');
@@ -263,7 +263,7 @@ export class WebGpuBackend {
     this.kernelCustomData = new Map();
 
     // set up flags for logger
-    configureLogger(env.logLevel!, !!env.debug);
+    configureLogger(env.logLevel, !!env.debug);
 
     // TODO: set up flags
 
@@ -341,10 +341,10 @@ export class WebGpuBackend {
     let queryReadBuffer: GPUBuffer;
     if (this.queryType !== 'none') {
       this.commandEncoder.resolveQuerySet(
-        this.querySet!,
+        this.querySet,
         0,
         this.pendingDispatchNumber * 2,
-        this.queryResolveBuffer!,
+        this.queryResolveBuffer,
         0,
       );
 
@@ -356,7 +356,7 @@ export class WebGpuBackend {
       this.pendingQueries.set(queryReadBuffer, this.pendingKernels);
       this.pendingKernels = [];
       this.commandEncoder.copyBufferToBuffer(
-        this.queryResolveBuffer!,
+        this.queryResolveBuffer,
         0,
         queryReadBuffer,
         0,
@@ -827,8 +827,7 @@ export class WebGpuBackend {
       return;
     }
 
-    // eslint-disable-next-line @typescript-eslint/no-explicit-any
-    (this.computePassEncoder as any).writeTimestamp(this.querySet, index);
+    this.computePassEncoder.writeTimestamp(this.querySet, index);
   }
   setQueryType(): void {
     this.queryType = 'none';
diff --git a/js/web/lib/wasm/jsep/backend-webnn.ts b/js/web/lib/wasm/jsep/backend-webnn.ts
index 0bb1b09687018..67779313d6d84 100644
--- a/js/web/lib/wasm/jsep/backend-webnn.ts
+++ b/js/web/lib/wasm/jsep/backend-webnn.ts
@@ -103,7 +103,7 @@ export class WebNNBackend {
   private mlOpSupportLimitsBySessionId = new Map<number, MLOpSupportLimits>();
 
   constructor(env: Env) {
-    configureLogger(env.logLevel!, !!env.debug);
+    configureLogger(env.logLevel, !!env.debug);
   }
 
   public get currentSessionId(): number {
diff --git a/js/web/lib/wasm/jsep/init.ts b/js/web/lib/wasm/jsep/init.ts
index 50fb26fef1d41..0476da3ebd586 100644
--- a/js/web/lib/wasm/jsep/init.ts
+++ b/js/web/lib/wasm/jsep/init.ts
@@ -200,7 +200,7 @@ export const init = async (
     // eslint-disable-next-line @typescript-eslint/no-require-imports, @typescript-eslint/no-var-requires
     const webGpuBackendImpl = require('./backend-webgpu').WebGpuBackend;
     const backend = new webGpuBackendImpl();
-    await backend.initialize(env, gpuAdapter!);
+    await backend.initialize(env, gpuAdapter);
 
     jsepInit('webgpu', [
       // backend
diff --git a/js/web/lib/wasm/proxy-worker/main.ts b/js/web/lib/wasm/proxy-worker/main.ts
index 163bac4eb676d..e65c8b5b0b579 100644
--- a/js/web/lib/wasm/proxy-worker/main.ts
+++ b/js/web/lib/wasm/proxy-worker/main.ts
@@ -109,7 +109,7 @@ if (isProxyWorker) {
         case 'init-wasm':
           initializeWebAssembly(message!.wasm).then(
             () => {
-              initRuntime(message!).then(
+              initRuntime(message).then(
                 () => {
                   postMessage({ type });
                 },
diff --git a/js/web/lib/wasm/run-options.ts b/js/web/lib/wasm/run-options.ts
index a0ef57df31129..41d10704ca911 100644
--- a/js/web/lib/wasm/run-options.ts
+++ b/js/web/lib/wasm/run-options.ts
@@ -41,8 +41,8 @@ export const setRunOptions = (options: InferenceSession.RunOptions): [number, nu
     }
 
     runOptionsHandle = wasm._OrtCreateRunOptions(
-      runOptions.logSeverityLevel!,
-      runOptions.logVerbosityLevel!,
+      runOptions.logSeverityLevel,
+      runOptions.logVerbosityLevel,
       !!runOptions.terminate!,
       tagDataOffset,
     );
diff --git a/js/web/lib/wasm/wasm-core-impl.ts b/js/web/lib/wasm/wasm-core-impl.ts
index 18c536d8d9217..4be34a01bac8f 100644
--- a/js/web/lib/wasm/wasm-core-impl.ts
+++ b/js/web/lib/wasm/wasm-core-impl.ts
@@ -92,7 +92,7 @@ const initOrt = (numThreads: number, loggingLevel: number): void => {
  */
 export const initRuntime = async (env: Env): Promise<void> => {
   // init ORT
-  initOrt(env.wasm.numThreads!, logLevelStringToEnum(env.logLevel));
+  initOrt(env.wasm.numThreads, logLevelStringToEnum(env.logLevel));
 };
 
 /**
@@ -955,7 +955,7 @@ export const run = async (
                   gpuBuffer,
                   download: async () => {
                     const arrayBuffer = await downloadDataFunction();
-                    const data = new (tensorTypeToTypedArrayConstructor(type!))(arrayBuffer);
+                    const data = new (tensorTypeToTypedArrayConstructor(type))(arrayBuffer);
                     return data as Tensor.DataTypeMap[Tensor.GpuBufferDataTypes];
                   },
                   dispose: () => {