Benchmark Overview

The provided JSON represents a JavaScript microbenchmark created on MeasureThat.net. The benchmark compares the execution times of three different operators: Array.indexOf, String.indexOf, and Object.lookup. These operators are used to find the index of a specific element within an array, string, or object.

Options Compared

1. Array.indexOf: This operator searches for the specified element in the array from left to right and returns its first occurrence.
2. String.indexOf: This operator searches for the specified character or substring in the string from left to right and returns its first occurrence.
3. Object.lookup (or Object["key"]): This operator uses bracket notation to access a property of an object by name.

Pros and Cons

• Array.indexOf:
  • Pros: Efficient for arrays with unique elements, can be faster than String.indexOf and Object.lookup.
  • Cons: May not find the last occurrence, and its performance can degrade if the array is large or contains many duplicate values.
• String.indexOf:
  • Pros: Can find the last occurrence of a character or substring in a string, relatively efficient for strings with unique characters.
  • Cons: Slower than Array.indexOf for arrays and may be less efficient for very long strings due to the need to scan from left to right.
• Object.lookup (or Object["key"]):
  • Pros: Fast access to properties of objects by name, can be used with both keys that exist in the object and those that do not.
  • Cons: May throw an error if the key does not exist, and its performance is generally slower than Array.indexOf due to the overhead of resolving the property.

Library Usage

None of the operators rely on any external libraries. They are built-in JavaScript functions.

Special JS Features or Syntax

The benchmark uses the following special JavaScript features:

• Bracket notation: The Object.lookup operator uses bracket notation (o[t]) to access properties of an object by name.
• Template literals: The String.indexOf test case uses template literals (s = '++--!=<<<>>';) to create a string with embedded expressions.

Alternative Approaches

In addition to the three operators being compared, alternative approaches for finding the index of an element in an array or string include:

• Linear search: A simple iterative approach that scans through the elements of an array or string until it finds a match.
• Binary search: An efficient algorithm for searching sorted arrays, which can be faster than linear search but requires the array to be sorted.

In general, Array.indexOf is a good choice when you need to find the first occurrence of an element in an array. String.indexOf and Object.lookup are better suited for finding the index of a character or property within a string or object.