jscost.md

https://github.com/cevek/jscost

conditionals

if (k) v = 1: 0.8ns

if (k) v = 1 else v = 0: 0.4ns

switch 10 cases (per case): 0.4ns

n1 && n2 && ... (per item): 1.7ns

n1 || n2 || ... (per item): 1.5ns

k == 0 ? 1 : k == 1 ? 2 : ... (10) (per cond): 0.5ns

k ? 1 : 0: 0.8ns


readKey

obj.a: 0.4ns

obj.a generic: 9ns

obj.x(non exists) generic: 9ns

obj.a mutated: 9ns

obj[prop]: 18ns

obj[prop] generic: 18ns

obj[prop] hashtable: 10ns

obj[non exist prop]: 93ns

obj[non exist prop] hashtable: 86ns


functions

inline function call: 0.4ns

function call: 3.7ns

fn.call(obj, val): 6ns

fn.apply(obj, args): 15ns

non optimized function call: 27ns


create objects

{}: 9ns

{a,b,c,d,e}: 9ns

{a,b,c,d,e,f,g,h,i,j}: 272ns

new A(){a,b,c,d,e}: 10ns

new A(){a,b,c,d,e,f,g,h,k,l}: 18ns


create objects 10 props (per key)

obj.key=1: 4.5ns

obj[strProp]=1: 18ns

obj[numProp]=1: 29ns

obj[strProp|numProp]=1: 32ns

obj = new A(); obj[prop]=1: 33ns

obj[prop]=1 hashtable: 27ns


read objectKeysValues (per key)

object.keys({a,b,c,d,e}): 17ns

object.keys + values({a,b,c,d,e}): 42ns

for in only keys {a,b,c,d,e}: 2.7ns

for in generic only keys {a,b,c,d,e}: 2.7ns

for in generic {a,b,c,d,e}: 4ns

for in generic(with hashtables) {a,b,c,d,e}: 28ns


objectKeys in hashtable (per key)

object.keys hashtable + values({a,b,c,d,e}): 82ns

for in hashtables {a,b,c,d,e}: 68ns

for in hashtables generic {a,b,c,d,e}: 77ns


readArray

arr[1]: 0.5ns

arr[i]: 1ns

arr[i] generic value: 1ns

uint8[i]: 1ns

uint16[i]: 1ns


createArray

empty array: 5ns

[0-9] const number: 5ns

[0-9] var number: 91ns

[0-9] const primitives(bool, number, string, null, not undefined): 5ns

[0-8] mixed: 14ns

[0-9] mixed: 95ns

[0-9] const number + undefined: 88ns

[] grow 0->9, mixed: 45ns

[0-9] primitives + set 5 vars, mixed: 24ns

new Array(10), empty: 14ns

new Array(10), mixed: 22ns

new Uint8Array(10), empty: 83ns

new Uint32Array(10), empty: 80ns