Some tweaks to Oliver Caldwell's excellent binary search Javascript function

search.js

binaryIndexOf=function (searchElement) {
  'use strict';

  var minIndex = 0;
  var maxIndex = this.length - 1;
  var currentIndex;
  var currentElement;

  console.warn("WE ARE LOOKING FOR: ",searchElement,"AKA",+searchElement);

  var circuitbreaker=0;
  while (minIndex <= maxIndex) {
    circuitbreaker++;
    currentIndex = (minIndex + maxIndex) >>1;
    currentElement = this[currentIndex];
    console.warn("minIndex: "+minIndex+" maxIndex: "+maxIndex+" currentIndex: "+currentIndex+" currentElement: "+currentElement);

    if (currentElement < searchElement) {
      minIndex = currentIndex+1;
    }
    else if (currentElement > searchElement) {
      maxIndex = currentIndex-1;
    }
    else {
      console.warn("KEY FOUND at: "+currentIndex);
      return currentIndex;
    }
    if(circuitbreaker>32) {
      console.warn("ERROR. circuitbreaker is: "+circuitbreaker);
      break;
    }
  }
  console.warn("KEY WAS NEVER FOUND, but it *would* be at: "+currentIndex+" min: "+minIndex+" max: "+maxIndex+". We found: "+currentElement+" at that index, and are looking for "+searchElement);
  return ~Math.max(minIndex,maxIndex);
}

search_test.js

"use strict";
var assert = require("assert");
var bsrch = require ("../search.js");

//requires 'mocha'
  
describe('##binaryIndexOf',function () {
  var arr=[1,2,3,4,5,6,7];
  var fun=function (i) {
    return bsrch.binaryIndexOf.call(arr,i);
  };
  var fun_assert=function (i,j) {
    assert.equal(fun(i),j,"Can't find "+i+" (got "+fun(i)+"["+~fun(i)+"], was looking for "+j+"["+~j+"])");
  };
  it('exact matches should work',function () {
    fun_assert(1,0);
    fun_assert(2,1);
    fun_assert(3,2);
    fun_assert(4,3);
    fun_assert(5,4);
  });
  it('mismatches should work',function () {
    fun_assert(0.5,~0);
    fun_assert(1.5,~1);
    fun_assert(2.5,~2);
    fun_assert(5.5,~5);
  });
});