deps

<script>
(function () {
  var store = []
  var timeout = null

  function checkDepsHaveLoadedForItem (item) {
    for(let i=0; i<item.deps.length; i++) {
      if(!window[item.deps[i]]) return false
    }
    return true
  }

  function checkStore () {
    for(var i=store.length-1; i>=0; i--) {
      var ready = checkDepsHaveLoadedForItem(store[i])
      if(ready) {
        store[i].cb()
        store.splice(i, 1)
      }
    }

    if(store.length) {
      timeout = setTimeout(checkStore, 500)
    } else {
      timeout = null
    }
  }

  window.runThisAfterScriptsLoad = function (cb, deps) {
    store.push({cb: cb, deps: deps})

    if(!timeout) {
      checkStore()
    }
  }
})()
</script>

<script>
runThisAfterScriptsLoad(function () {
  console.log("https://www.youtube.com/watch?v=tFlAFo78xoQ")
},
['jQuery'])

runThisAfterScriptsLoad(function () {
  console.log("This shall never be seen!")
},
['theVarThatNeverGetsDefined'])

</script>

<script
src="https://code.jquery.com/jquery-3.4.1.min.js"
integrity="sha256-CSXorXvZcTkaix6Yvo6HppcZGetbYMGWSFlBw8HfCJo="
crossorigin="anonymous"></script>