Several Ways of Generating Unique ID from JavaScript

Feasible scheme

1. Math. random that generates a random number of [0, 1]

// What I generated this time is: 0.5834165740043102 
Math.random();

2. Get the current timestamp Date. now

// Now the timestamp is 1482645606622
Date.now();

3. The string Number. toString that converts decimal to other decimal

// Will 1482645606622 Convert to 2 Binary system: 10101100100110100100100001001000011011110 
(1482645606622).toString(2);

// Convert to 16 Binary system: 159349090de MongDB In ObjectID Is 24 Bit 16 Binary number  
(1482645606622).toString(16);

// Maximum binary support conversion 36 In binary, the characters used are 0-9a-z  : ix48wvry 
(1482645606622).toString(36);

Improvement 1: Random Numbers + toString ()

1. Random number version

/**
 *  Generate 1 Use non-repetitive ID
 */
function GenNonDuplicateID(){
 return Math.random().toString()
}

// Generate 1 A similarity  0.1283460319177394 Adj. ID
GenNonDuplicateID()

2. Random number version hexadecimal version

/**
 *  Generate 1 Use non-repetitive ID
 */
function GenNonDuplicateID(){
 return Math.random().toString(16)
}

// Function generates a similar  0.c1615913fa915  Adj. ID
GenNonDuplicateID()

3. Random number version 36-ary version

/**
 *  Generate 1 Use non-repetitive ID
 */
function GenNonDuplicateID(){
 return Math.random().toString(36)
}

// Function generates a similar  0.hefy7uw6ddzwidkwcmxkzkt9  Adj. ID
GenNonDuplicateID()

4. Random number version 36-ary version

/**
 *  Generate 1 Use non-repetitive ID
 */
function GenNonDuplicateID(){
 return Math.random().toString(36).substr(2)
}

// Function generates a similar  8dlv9vabygks2cbg1spds4i  Adj. ID
GenNonDuplicateID()

Summarize

Advantage: Using toString's binary conversion can achieve shorter string representation of more ranges

Disadvantages: Using one random number as ID, with the accumulation of usage times, the same two ID will inevitably appear

Modified version 2

1. Introducing timestamp + 36-ary version

/**
 *  Generate 1 Use non-repetitive ID
 */
function GenNonDuplicateID(){
 let idStr = Date.now().toString(36)
 idStr += Math.random().toString(36).substr(2)
 return idStr
}

// Function generates a similar  ix49sfsnt7514k5wpflyb5l2vtok9y66r  Adj. ID
GenNonDuplicateID()

2. Introducing timestamp + 36-ary version + random number length control

/**
 *  Generate 1 Use non-repetitive ID
 */
function GenNonDuplicateID(randomLength){
 let idStr = Date.now().toString(36)
 idStr += Math.random().toString(36).substr(2,randomLength)
 return idStr
}

// GenNonDuplicateID(3)  Will generate a similar  ix49wl2978w  Adj. ID
GenNonDuplicateID(3)

However, the first few bits of ID generated in this way are always the same.

3. Introducing timestamp + random number preamble 36-ary + random number length control

/**
 *  Generate 1 Use non-repetitive ID
 */
function GenNonDuplicateID(randomLength){
 return Number(Math.random().toString().substr(2,randomLength) + Date.now()).toString(36)
}
//GenNonDuplicateID() Will generate  rfmipbs8ag0kgkcogc  Similar ID
GenNonDuplicateID()

Summarize

Using only timestamps, there is one that can be accessed by multiple people in the same time. Adding random numbers can achieve only 1. Coupled with custom length, UUID is more flexible.

Summarize

Universal solution:

// Now the timestamp is 1482645606622
Date.now();

0

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