old_contents: 
  /**
   * Test performancce of array concat and unshift.
   *
   * @see {@link https://www.measurethat.net/Benchmarks/Show/9225/0/colorfulcakechen-array-concat-unshift-f38d5e6c5a6a0096f}
   */
  
  /**
   * A test set.
   */
  class TestSet {
  
    /**
     */
    constructor( arrayListLength ) {
  
      this.arrayListLength = arrayListLength;
      this.arrayList = new Array( arrayListLength );
  
      for ( let i = 0; i < this.arrayListLength; ++i ) {
        this.arrayList[ i ] = new Array( 1 );
        this.arrayList[ i ][ 0 ] = i;
      }
    }
  
    test_ArrayConcat() {
      let result = [];
      for ( let i = 0; i < this.arrayListLength; ++i ) {
        result = result.concat( this.arrayList[ i ] );
      }
    }
  
    test_ArrayUnshift() {
      let result = [];
      for ( let i = ( this.arrayListLength - 1 ); i >= 0; --i ) {
        result.unshift( ...this.arrayList[ i ] );
      }
    }
  
    // Testing whether the results of different implementation are the same. Also, pre-compile the codes.
    async testCaseLoader() {
      this.test_ArrayConcat();
      this.test_ArrayUnshift();
    }
   
  }
  
  
  globalThis.testSet = new TestSet( 100 );
  
new_contents: 
  /**
   * Test performancce of array concat and unshift.
   *
   * @see {@link https://www.measurethat.net/Benchmarks/Show/9225/1/colorfulcakechen-array-concat-unshift-d01e94e8696ce742e}
   */
  
  /**
   * A test set.
   */
  class TestSet {
  
    /**
     */
    constructor( arrayListLength ) {
  
      this.arrayListLength = arrayListLength;
      this.arrayList = new Array( arrayListLength );
  
      for ( let i = 0; i < this.arrayListLength; ++i ) {
        this.arrayList[ i ] = new Array( 1 );
        this.arrayList[ i ][ 0 ] = i;
      }
    }
  
    test_ArrayConcat() {
      let result = [];
      for ( let i = 0; i < this.arrayListLength; ++i ) {
        result = result.concat( this.arrayList[ i ] );
      }
    }
  
    test_ArrayUnshift() {
      let result = [];
      for ( let i = ( this.arrayListLength - 1 ); i >= 0; --i ) {
        result.unshift( ...this.arrayList[ i ] );
      }
    }
  
    // Testing whether the results of different implementation are the same. Also, pre-compile the codes.
    async testCaseLoader() {
      this.test_ArrayConcat();
      this.test_ArrayUnshift();
    }
   
  }
  
  
  globalThis.testSet = new TestSet( 100 );
  
subject: Update jsPerf_ArrayConcatUnshift.js