The top ten rounding methods tutorials for JavaScript

1. parseInt()

// js built-in function, note that accepting parameters is string, so there is a type conversion when calling this methodparseInt("1.5555") // =&gt; 1

2. (0)

// Pay attention to the string returned by toFixed. If you want to obtain integers, you still need to do type conversion.1.(0) // =&gt; "1"

3. ()

// Round up(1.5555) // =&gt; 2

4. ()

// Round down(1.5555) // =&gt; 1

5. ()

// Rounding(1.5555) // =&gt; 2

(1.4999) // =&gt; 1

6. ()

// Abandon decimals to round(1.5555) // =&gt; 1

7. Double bitwise non-rounding

// Use bit operation to round, only 32-bit signed integer numbers are supported, and the decimal places will be discarded, the same below~~1.5555 // =&gt; 1

8. Rotate or round

1.5555 | 0 // => 1

9. Bitwise XOR rounding

1.5555^0 // => 1

10. Turn left by 0 bits

1.5555<<0 // => 1

Among the 10 rounding methods mentioned above, the most commonly used estimates are the first two [I split ~~]. However, from a performance perspective, bit operation rounding and Math function perform the best, with the built-in method parseInt second, and toFixed the worst performance.

Here are the results of Benchmark tests, which prove that toFixed has the worst performance:

darwin x64
Integer rounding#getNum1#parseInt x 210,252,532 ops/sec ±2.74% (85 runs sampled)
Integer rounding#getNum2#toFixed x 3,281,188 ops/sec ±1.54% (86 runs sampled)
Integer rounding#getNum3# x 778,272,700 ops/sec ±3.97% (87 runs sampled)
Integer rounding#getNum4# x 816,990,140 ops/sec ±0.54% (88 runs sampled)
Integer rounding#getNum5# x 814,868,414 ops/sec ±0.65% (88 runs sampled)
Integer rounding#getNum6# x 821,032,596 ops/sec ±0.54% (91 runs sampled)
Integer rounding#getNum7#~~num x 813,589,741 ops/sec ±0.67% (90 runs sampled)
Integer rounding#getNum8#num | 0 x 815,070,107 ops/sec ±0.65% (90 runs sampled)
Integer rounding#getNum9#num ^ 0 x 812,635,464 ops/sec ±0.74% (90 runs sampled)
Integer rounding#getNum10#num &lt;&lt; 0 x 819,230,753 ops/sec ±0.49% (91 runs sampled)
Fastest is Integer rounding#getNum6#, round the integer#getNum10#num << 0

Benchmarksource code

refer to

/zh-CN/docs/…

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