git ssb

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var resolve = require('./resolve')
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var isObservable = require('./is-observable')
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module.exports = function throttledWatch (obs, minDelay, listener, opts) {
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  var throttling = false
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  var lastRefreshAt = 0
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  var lastValueAt = 0
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  var throttleTimer = null
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  var broadcastInitial = !opts || opts.broadcastInitial !== false
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  // default delay is 20 ms
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  minDelay = minDelay || 20
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  // run unless opts.broadcastInitial === false
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  if (broadcastInitial) {
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    listener(resolve(obs))
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  }
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  if (isObservable(obs)) {
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    return obs(function (v) {
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      if (!throttling) {
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        if (Date.now() - lastRefreshAt > minDelay) {
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          refresh()
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        } else {
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          throttling = true
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          throttleTimer = setInterval(refresh, minDelay)
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        }
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      }
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      lastValueAt = Date.now()
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    })
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  } else {
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    return noop
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  }
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  function refresh () {
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    lastRefreshAt = Date.now()
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    listener(obs())
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    if (throttling && lastRefreshAt - lastValueAt > minDelay) {
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      throttling = false
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      clearInterval(throttleTimer)
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    }
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  }
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}
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function noop () {}
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