feat: write data to the specified byte in the buffer.

Author: ghosind

src/dynamicBuffer.ts

@@ -203,6 +203,17 @@ export class DynamicBuffer {
 
         return Reflect.get(target, p, receiver);
       },
+      set: (target: this, p: string | symbol, newValue: any, receiver: any) => {
+        if (Reflect.has(target, p)) {
+          return Reflect.set(target, p, newValue, receiver);
+        }
+        if (Number(p) >= 0) {
+          Reflect.apply(Reflect.get(target, 'writeByte', receiver), target, [newValue, Number(p)]);
+          return true;
+        }
+
+        return Reflect.set(target, p, newValue, receiver);
+      },
     });
   }
 
@@ -1048,6 +1059,20 @@ export class DynamicBuffer {
     this.size = newSize;
   }
 
+  /**
+   * Writes data to the specified position in the buffer, and skip if out of used range.
+   *
+   * @param data Data to write to buffer.
+   * @param offset The position to write data.
+   */
+  private writeByte(data: any, offset: number) {
+    if (!this.buffer || this.length === 0 || offset >= this.length) {
+      return;
+    }
+
+    this.buffer[offset] = data;
+  }
+
   /**
    * Write data into internal buffer with the specified offset.
    *

test/read.spec.ts

@@ -4,7 +4,7 @@ import { describe, it } from 'mocha';
 import { DynamicBuffer } from '../src';
 
 describe('Get by index tests', () => {
-  it('Test getting by index with legal ranges', () => {
+  it('Test getting by index with valid position', () => {
     const buffer = new DynamicBuffer();
     const str = 'Hello world';
 

test/write.spec.ts

@@ -4,6 +4,31 @@ import { describe, it } from 'mocha';
 
 import { DynamicBuffer } from '../src';
 
+describe('Set by index tests', () => {
+  it('Test set by index with valid position', () => {
+    const buffer = new DynamicBuffer('hello world');
+
+    buffer[0] = 72;
+    assert.equal(buffer.toString(), 'Hello world');
+  });
+
+  it('Test getting by index with a negative offset', () => {
+    const buffer = new DynamicBuffer('Hello world');
+
+    buffer[-1] = 33; // !
+
+    assert.equal(buffer.toString(), 'Hello world');
+  });
+
+  it('Test getting by index with a offset larger than buffer length', () => {
+    const buffer = new DynamicBuffer('Hello world');
+
+    buffer[buffer.length] = 33; // !
+
+    assert.equal(buffer.toString(), 'Hello world');
+  });
+});
+
 describe('Append tests', () => {
   it('Test appending string', () => {
     const buffer = new DynamicBuffer();