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ccsunny
ccsunny

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V8 fast-property in Object

#javascript #performance #node

V8 Object takeaway

  • Array-indexed properties are stored in a separate elements store.
  • Named properties are stored in the properties store.
  • Elements and properties can either be arrays or dictionaries.
  • Each JavaScript object has a HiddenClass associated that keeps

Element 

function Foo() {
    this[100] = 'test-100'
    this[1] = 'test-1'
    this["B"] = 'bar-B'
    this[50] = 'test-50'
    this[9] = 'test-9'
    this[8] = 'test-8'
    this[3] = 'test-3'
    this[5] = 'test-5'
    this["A"] = 'bar-A'
    this["C"] = 'bar-C'
}
var bar = new Foo()
for(key in bar){
    console.log(`index:${key} value:${bar[key]}`)
}
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Property 

function Foo2(property_num,element_num) {
    for (let i = 0; i < element_num; i++) {
      this[i] = `element${i}`
    }
    for (let i = 0; i < property_num; i++) {
    let ppt = `property${i}`
    this[ppt] = ppt
}}
var bar2 = new Foo2(20, 10)
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Resources

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