计算字符串的理论长度,双字节字符(包含汉字在内)长度计2,ASCII字符计1
办法1:应用match:
export function getByteLenMatch(data) { let result = 0; for (let s of data) { result += s.match(/[^\\x00-\\xff]/ig) == null ? 1 : 2; } return result;}办法2:应用replace:
export function getByteLenReplace(data) { return data.replace(/[^\\x00-\\xff]/ig, "aa").length;}测试代码:
let testData = new Array(50000000).fill("哈").toString(); for (let i = 0; i < 3; i++) { console.time("getByteLenMatch"); getByteLenMatch(testData); console.timeEnd("getByteLenMatch"); console.time("getByteLenReplace"); getByteLenReplace(testData); console.timeEnd("getByteLenReplace"); }性能比拟(单位ms):
| 字符串长度 | match | replace |
|---|---|---|
| 50,000,000 | 8051 | 8626 |
| 50,000,000 | 9351 | 8019 |
| 50,000,000 | 10384 | 7512 |
| 10,000,000 | 1631 | 1783 |
| 10,000,000 | 1646 | 1343 |
| 10,000,000 | 1663 | 1372 |
| 5,000,000 | 799 | 728 |
| 5,000,000 | 822 | 806 |
| 5,000,000 | 884 | 645 |
| 1,000,000 | 165 | 128 |
| 1,000,000 | 166 | 143 |
| 1,000,000 | 170 | 113 |
| 500,000 | 84 | 58 |
| 500,000 | 83 | 54 |
| 500,000 | 86 | 61 |
| 100,000 | 20 | 7 |
| 100,000 | 18 | 5 |
| 100,000 | 20 | 5 |
| 50,000 | 11.79 | 3.01 |
| 50,000 | 10.39 | 2.68 |
| 50,000 | 11.99 | 2.82 |
| 10,000 | 4.13 | 0.60 |
| 10,000 | 4.32 | 0.59 |
| 10,000 | 5.48 | 0.58 |
| 5,000 | 1.88 | 0.31 |
| 5,000 | 1.36 | 0.33 |
| 5,000 | 2.71 | 0.31 |
| 1,000 | 1.67 | 0.07 |
| 1,000 | 0.21 | 0.07 |
| 1,000 | 1.02 | 0.06 |
| 500 | 0.0840 | 0.0322 |
| 500 | 0.0820 | 0.0332 |
| 500 | 0.0840 | 0.0320 |
| 100 | 0.0229 | 0.0100 |
| 100 | 0.0432 | 0.0149 |
| 100 | 0.0471 | 0.0161 |
在大数据量状况下，replace性能首次会劣于match，屡次执行后会优于match，小数据量状况下，replace性能优于match
作者：点墨
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