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Substr vs slice vs replace
(version: 0)
Comparing performance of:
Replace vs Substr vs Slice
Created:
6 years ago
by:
Guest
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Tests:
Replace
let str = "someverylongstringthatkeepsonlistingwordsthatdonotserveranyspecificpurposeotherthantestingpurposeforperformancedidyouknowthatsomeverylongstringcouldbegoingonforeverwhenandonlywhen$"; for (let i = 0; i < 500000; ++i) { str = str.replace('$', ''); }
Substr
let str = "someverylongstringthatkeepsonlistingwordsthatdonotserveranyspecificpurposeotherthantestingpurposeforperformancedidyouknowthatsomeverylongstringcouldbegoingonforeverwhenandonlywhen$"; for (let i = 0; i < 500000; ++i) { str = str.substr(0, str.length-1); }
Slice
let str = "someverylongstringthatkeepsonlistingwordsthatdonotserveranyspecificpurposeotherthantestingpurposeforperformancedidyouknowthatsomeverylongstringcouldbegoingonforeverwhenandonlywhen$"; for (let i = 0; i < 500000; ++i) { str = str.slice(0, -1); }
Rendered benchmark preparation results:
Suite status:
<idle, ready to run>
Run tests (3)
Previous results
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Test case name
Result
Replace
Substr
Slice
Fastest:
N/A
Slowest:
N/A
Latest run results:
Run details:
(Test run date:
11 months ago
)
User agent:
Mozilla/5.0 (X11; Linux x86_64; rv:139.0) Gecko/20100101 Firefox/139.0
Browser/OS:
Firefox 139 on Linux
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Embed Benchmark Result
<iframe src="https://measurethat.net/Embed?id=608360" width="100%" height="500px"></iframe>
Test name
Executions per second
Replace
122.0 Ops/sec
Substr
1104.3 Ops/sec
Slice
1149.0 Ops/sec
Autogenerated LLM Summary
(model
llama3.2:3b
, generated one year ago):
Let's dive into the details of this JavaScript benchmark. **What is tested?** The provided JSON represents a benchmark that compares three different approaches to remove the last character from a long string: `replace()`, `substr()` (also known as `substring()`), and `slice()`. The test creates a very long string containing only one dollar sign (`$`) and then repeatedly applies each of these methods to remove the last character. **Options compared** The three options being compared are: 1. **`replace()`**: Replaces the first occurrence of the specified value (in this case, `$`) with an empty string. 2. **`substr()`** (also known as `substring()`): Returns a substring of the original string, starting from the beginning and ending at the specified position (`str.length-1`). 3. **`slice()`**: Creates a new string that includes all characters before the specified position (`0, -1`) in the original string. **Pros and cons** Here are some pros and cons for each approach: * `replace()`: + Pros: Simple and efficient, as it only requires a single operation to replace the character. + Cons: May not be suitable for strings where the character to be replaced is not the first occurrence. Additionally, if the string contains multiple consecutive occurrences of the character, this method may be slower due to repeated replacements. * `substr()`: + Pros: Allows for precise control over the substring extracted from the original string. + Cons: Requires specifying the starting and ending positions, which can lead to more complex code. Additionally, it creates a new string object, which may not be desirable in terms of memory usage. * `slice()`: + Pros: Creates a new string that includes all characters before the specified position, which can be more efficient than modifying the original string. + Cons: Requires specifying two positions (start and end), which can lead to more complex code. Additionally, it may not be suitable for strings where the character to be removed is not at the end. **Library and purpose** None of the libraries are explicitly mentioned in the provided benchmark JSON. However, `slice()` was introduced in ECMAScript 5 (ES5) as a part of the standard library. **Special JS feature or syntax** The use of `let` with the `const` keyword is not unusual in modern JavaScript code, but it's used here to declare variables that are scoped to the benchmark test. Additionally, the `++i` expression in the loops is a shorthand for incrementing the variable `i`. **Other considerations** When choosing an approach for string manipulation, consider factors such as: * Performance: Are you dealing with large strings or frequently updating them? Optimize your approach accordingly. * Memory usage: Is memory usage a concern in your application? Choose approaches that minimize creating new string objects. * Code complexity and maintainability: How complex is your codebase, and how much time will it take to modify the code if needed? **Alternatives** Some alternative approaches for removing characters from strings include: * Using `Array.prototype.splice()` or other array methods to manipulate the string as an array * Utilizing regex with the `replace()` method * Creating a custom function that iterates over the string and removes characters using indexing Keep in mind that each approach has its trade-offs, and the best choice depends on your specific use case.
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