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# Uses a binary search algorithm to locate a value in the specified array.
binary_search = (items, value) ->
start = 0
stop = items.length - 1
pivot = Math.floor (start + stop) / 2
while items[pivot] isnt value and start < stop
# Adjust the search area.
stop = pivot - 1 if value < items[pivot]
start = pivot + 1 if value > items[pivot]
# Recalculate the pivot.
pivot = Math.floor (stop + start) / 2
# Make sure we've found the correct value.
if items[pivot] is value then pivot else -1
# Test the function.
console.log 2 is binary_search [10, 20, 30, 40, 50], 30
console.log 4 is binary_search [-97, 35, 67, 88, 1200], 1200
console.log 0 is binary_search [0, 45, 70], 0
console.log -1 is binary_search [0, 45, 70], 10
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