Javascript Performence Tests

js-perf-tests.md

Javascript Performence Tests

• for (...) {}
• array copy: new Array(len) and copy in loop is fastest
• concat vs unshift
• Visitor(eval seems no performence degradation)
• Cache: no difference, but cached faster in IE 11 (except array item cache)
• Enumerate Object Properties
• apply arguments
• create object: (new Object() vs {})
• create array: (new Array() vs [])
• init object: (new Object() vs {})
• get value from object: (new Object() vs {}): not stable, seems almost no difference.
• flag operation: no difference, but !! and ! faster in IE 11
• check reference nil vs check another flag: check flag is faster
• check property exists
• Object literal vs custom constructor: in some browser literal returns by function is fastest
• Get Set

Toolsets

jsperf 扩展：https://gist.github.com/jareguo/99cf83d1d851b53e37963316afadbcc7
Benchmark playground

References

• Let’s get those Javascript Arrays to work fast
• Google Closure: How not to write JavaScript
• node.js背后的引擎V8及优化技术
• Breaking the JavaScript Speed Limit with V8 (Youtube) | PPT
• Optimization killers
• Writing Fast, Memory-Efficient JavaScript EN | ZH
• ES6性能测试
• JS Tips