[tfjs-node] replace deprecated utils (#8425)

Co-authored-by: Matthew Soulanille <msoulanille@google.com>

Author: tharvik

tfjs-node/src/kernels/TopK.ts

@@ -16,7 +16,6 @@
  */
 
 import {KernelConfig, scalar, TopK, TopKAttrs, TopKInputs} from '@tensorflow/tfjs';
-import {isNullOrUndefined} from 'util';
 
 import {createTensorsTypeOpAttr, NodeJSKernelBackend} from '../nodejs_kernel_backend';
 
@@ -28,8 +27,8 @@ export const topKConfig: KernelConfig = {
     const backend = args.backend as NodeJSKernelBackend;
     const {k, sorted} = args.attrs as unknown as TopKAttrs;
 
-    const kCount = isNullOrUndefined(k) ? 1 : k;
-    const isSorted = isNullOrUndefined(sorted) ? true : sorted;
+    const kCount = k ?? 1;
+    const isSorted = sorted ?? true;
     const opAttrs = [
       {name: 'sorted', type: backend.binding.TF_ATTR_BOOL, value: isSorted},
       createTensorsTypeOpAttr('T', x.dtype),

tfjs-node/src/nodejs_kernel_backend.ts

@@ -17,7 +17,6 @@
 
 import * as tf from '@tensorflow/tfjs';
 import {backend_util, BackendTimingInfo, DataId, DataType, KernelBackend, ModelTensorInfo, Rank, Scalar, scalar, ScalarLike, Tensor, Tensor1D, Tensor2D, Tensor3D, Tensor4D, TensorInfo, tidy, util} from '@tensorflow/tfjs';
-import {isArray, isNullOrUndefined} from 'util';
 
 import {encodeInt32ArrayAsInt64, Int64Scalar} from './int64_tensors';
 import {TensorMetadata, TFEOpAttr, TFJSBinding} from './tfjs_binding';
@@ -740,7 +739,7 @@ export function getTFDType(dataType: tf.DataType): number {
 export function createTensorsTypeOpAttr(
     attrName: string,
     tensorsOrDtype: tf.Tensor|tf.Tensor[]|tf.DataType): TFEOpAttr {
-  if (isNullOrUndefined(tensorsOrDtype)) {
+  if (tensorsOrDtype === null || tensorsOrDtype === undefined) {
     throw new Error('Invalid input tensors value.');
   }
   return {
@@ -757,18 +756,18 @@ export function createTensorsTypeOpAttr(
 export function createOpAttr(
     attrName: string, tensorsOrDtype: tf.Tensor|tf.Tensor[]|tf.DataType,
     value: ScalarLike): TFEOpAttr {
-  if (isNullOrUndefined(tensorsOrDtype)) {
+  if (tensorsOrDtype === null || tensorsOrDtype === undefined) {
     throw new Error('Invalid input tensors value.');
   }
   return {name: attrName, type: nodeBackend().binding.TF_BOOL, value};
 }
 
 /** Returns the dtype number for a single or list of input Tensors. */
 function getTFDTypeForInputs(tensors: tf.Tensor|tf.Tensor[]): number {
-  if (isNullOrUndefined(tensors)) {
+  if (tensors === null || tensors === undefined) {
     throw new Error('Invalid input tensors value.');
   }
-  if (isArray(tensors)) {
+  if (Array.isArray(tensors)) {
     for (let i = 0; i < tensors.length; i++) {
       return getTFDType(tensors[i].dtype);
     }