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code/link/link-frontend/test.js

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+function Snowflake() {
+  this.epoch = 1698796800000 // 自定义起始时间（毫秒）
+  this.machineId = 1 // 固定 machineId
+  this.sequence = 0
+  this.lastTimestamp = -1
+
+  this.sequenceBits = 12
+  this.machineBits = 10
+  this.maxSequence = 2 ** this.sequenceBits - 1 // 4095
+}
+
+// 获取当前时间（毫秒）
+Snowflake.prototype.currentTime = function () {
+  return Date.now()
+}
+
+// 等待下一毫秒
+Snowflake.prototype.waitNextMillisecond = function (lastTimestamp) {
+  let timestamp = this.currentTime()
+  while (timestamp <= lastTimestamp) {
+    timestamp = this.currentTime()
+  }
+  return timestamp
+}
+
+// 生成 BigInt ID
+Snowflake.prototype.nextId = function () {
+  let timestamp = this.currentTime()
+
+  if (timestamp < this.lastTimestamp) {
+    throw new Error('Clock moved backwards. Refusing to generate id.')
+  }
+
+  if (timestamp === this.lastTimestamp) {
+    this.sequence = (this.sequence + 1) & this.maxSequence
+    if (this.sequence === 0) {
+      timestamp = this.waitNextMillisecond(this.lastTimestamp)
+    }
+  }
+  else {
+    this.sequence = 0
+  }
+
+  this.lastTimestamp = timestamp
+
+  const id
+    = (BigInt(timestamp - this.epoch) << BigInt(this.machineBits + this.sequenceBits))
+      | (BigInt(this.machineId) << BigInt(this.sequenceBits))
+      | BigInt(this.sequence)
+
+  return id
+}
+
+// 返回固定长度字符串 ID（适合数据库存储）
+Snowflake.prototype.nextIdStr = function (padLength = 20) {
+  return this.nextId().toString().padStart(padLength, '0')
+}