How might I find the largest number contained in a JavaScript array

Question

I have a simple JavaScript Array object containing a few numbers    267  306  108    Is there a function that would find the largest number in this array

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The easiest syntax  with the new spread operator   var arr    1  2  3   var max   Math max    arr     Source   Mozilla MDN

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To find the largest number in an array you just need to use Math max    arrayName    It works like this  let myArr    1  2  3  4  5  6   console log Math max    myArr     To learn more about Math max  https   developer mozilla org en-US docs Web JavaScript Reference Global Objects Math max

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https   developer mozilla org en-US docs Web JavaScript Reference Global Objects Math max    x000D   x000D  const inputArray     1  3  4  9  16  2  20  18   x000D  const maxNumber   Math max    inputArray   x000D  console log maxNumber   x000D   x000D   x000D

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Don t forget that the wrap can be done with Function prototype bind  giving you an  all-native  function   var aMax   Math max apply bind Math max  Math   aMax  1  2  3  4  5       5

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You can try this  var arr    267  306  108   var largestNum   0  for i 0  i lt arr length  i         if arr i   gt  largest        var largest   arr i          console log largest

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A recursive approach on how to do it using ternary operators   x000D   x000D  const findMax    arr  max  i    gt  arr length     i   max   x000D    findMax arr  arr i   gt  max   arr i    max    i  x000D   x000D  const arr    5  34  2  1  6  7  9  3   x000D  const max   findMax arr  arr 0   0  x000D  console log max   x000D   x000D   x000D

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You could also extend Array to have this function and make it part of every array   Array prototype max   function   return Math max apply  Math  this     myArray    1 2 3    console log  myArray max

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Use  var arr    1  2  3  4    var largest   arr reduce function x y        return  x  gt  y    x   y       console log largest

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Use Array reduce   0 1 2 3 4  reduce function previousValue  currentValue     return Math max previousValue currentValue

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I ve found that for bigger arrays   100k elements   it actually pays to simply iterate the array with a humble for loop  performing  30  better than Math max apply     function mymax a        var m   -Infinity  i   0  n   a length       for    i    n    i            if  a i   gt  m                m   a i                        return m      Benchmark results

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Simple one liner     sort   pop

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You could sort the array in descending order and get the first item    267  306  108  sort function a b  return b-a    0

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Finding max and min value the easy and manual way  This code is much faster than Math max apply  I have tried up to 1000k numbers in array   function findmax array        var max   0      var a   array length      for  counter 0 counter lt a counter                  if  array counter   gt  max                        max   array counter                       return max     function findmin array        var min   array 0       var a   array length      for  counter 0 counter lt a counter                  if  array counter   lt  min                        min   array counter                       return min

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x000D   x000D  var nums    1 4 5 3 1 4 7 8 6 2 1 4   nums sort    nums reverse    alert nums 0    x000D   x000D   x000D   Simplest Way  var nums    1 4 5 3 1 4 7 8 6 2 1 4   nums sort    nums reverse    alert nums 0

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You can use the apply function  to call Math max  var array    267  306  108   var largest   Math max apply Math  array      306  How does it work  The apply function is used to call another function  with a given context and arguments  provided as an array  The min and max functions can take an arbitrary number of input arguments  Math max val1  val2       valN  So if we call  Math min apply Math   1  2  3  4     The apply function will execute  Math min 1  2  3  4    Note that the first parameter  the context  is not important for these functions since they are static  They will work regardless of what is passed as the context

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One for of loop solution    x000D   x000D  const numbers    2  4  6  8  80  56  10   x000D   x000D   x000D  const findMax       numbers    gt    x000D    let currentMax   numbers 0      2 x000D   x000D    for  const number of numbers    x000D      if  number  gt  currentMax    x000D        console log number  currentMax   x000D        currentMax   number  x000D        x000D      x000D    console log  Largest    currentMax   x000D    return currentMax  x000D     x000D   x000D  findMax    numbers   x000D   x000D   x000D

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Try this  function largestNum arr      var currentLongest   arr 0     for  var i 0  i lt  arr length  i         if  arr i   gt  currentLongest         currentLongest   arr i               return currentLongest

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My solution to return largest numbers in arrays  const largestOfFour   arr   gt        let arr2           arr map e   gt            let numStart   -Infinity          e forEach num   gt                if  num  gt  numStart                    numStart   num                                    arr2 push numStart              return arr2

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You can also use forEach    x000D   x000D  var maximum   Number MIN SAFE INTEGER  x000D   x000D  var array    -3  -2  217  9  -8  46   x000D  array forEach function value   x000D    if value  gt  maximum    x000D      maximum   value  x000D      x000D      x000D   x000D  console log maximum      217 x000D   x000D   x000D

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Find Max and Min value using Bubble Sort   x000D   x000D      var arr    267  306  108   x000D   x000D      for i 0  k 0  i lt arr length  i      x000D        for j 0  j lt i  j      x000D          if arr i  gt arr j     x000D            k   arr i   x000D            arr i    arr j   x000D            arr j    k  x000D            x000D          x000D        x000D      console log  largest Number     arr 0    x000D      console log  Smallest Number     arr arr length-1    x000D   x000D   x000D

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let array    267  306  108  let longest   Math max    array

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As per  Quasimondo s comment  which seems to have been largely missed  the below seems to have the best performance as shown here  https   jsperf com finding-maximum-element-in-an-array  Note that while for the array in the question  performance may not have a significant effect  for large arrays performance becomes more important  and again as noted using Math max   doesn t even work if the array length is more than 65535  See also this answer   function largestNum arr        var d   data      var m   d d length - 1       for  var i   d length - 1  --i  gt  -1           if  d i   gt  m  m   d i             return m

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Almost all of the answers use Math max apply   which is nice and dandy  but it has limitations  Function arguments are placed onto the stack which has a downside - a limit  So if your array is bigger than the limit it will fail with RangeError  Maximum call stack size exceeded  To find a call stack size I used this code  var ar       for  var i   1  i  lt  100 99999  i        ar push 1     try       var max   Math max apply Math  ar       catch e        console log  Limit reached    i   error is    e       break         It proved to be biggest on Firefox on my machine - 591519  This means that if you array contains more than 591519 items  Math max apply   will result in RangeError  The best solution for this problem is iterative way  credit  https   developer mozilla org    max   -Infinity  min    Infinity   for  var i   0  i  lt  numbers length  i        if  numbers i   gt  max      max   numbers i     if  numbers i   lt  min      min   numbers i      I have written about this question on my blog here

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Should be quite simple  var countArray    1 2 3 4 5 1 3 51 35 1 357 2 34 1 3 5 6    var highestCount   0  for var i 0  i lt  countArray length  i             if countArray i  gt  highestCount       highestCount   countArray i         console log  quot Highest Count is  quot    highestCount

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Yes  of course there exists Math max apply null  23 45 67 -45    and the result is to return 67

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I m not a JavaScript expert  but I wanted to see how these methods stack up  so this was good practice for me  I don t know if this is technically the right way to performance test these  but I just ran them one right after another  as you can see in my code  Sorting and getting the 0th value is by far the worst method  and it modifies the order of your array  which may not be desirable   For the others  the difference is negligible unless you re talking millions of indices  Average results of five runs with a 100 000-index array of random numbers   reduce took 4 0392 ms to run Math max apply took 3 3742 ms to run sorting and getting the 0th value took 67 4724 ms to run Math max within reduce   took 6 5804 ms to run custom findmax function took 1 6102 ms to run   var performance   window performance  function findmax array        var max   0          a   array length          counter      for  counter 0  counter lt a  counter                  if  array counter   gt  max                        max   array counter                      return max    function findBiggestNumber num      var counts        var i   for  i   0  i  lt  num  i            counts push Math random           var a  b    a   performance now     var biggest   counts reduce function highest  count            return highest  gt  count   highest   count          0    b   performance now     console log  reduce took      b - a      ms to run      a   performance now     var biggest2   Math max apply Math  counts    b   performance now     console log  Math max apply took      b - a      ms to run      a   performance now     var biggest3   counts sort function a b   return b-a    0    b   performance now     console log  sorting and getting the 0th value took      b - a      ms to run      a   performance now     var biggest4   counts reduce function highest  count            return Math max highest  count           0    b   performance now     console log  Math max within reduce   took      b - a      ms to run      a   performance now     var biggest5   findmax counts    b   performance now     console log  custom findmax function took      b - a      ms to run     console log biggest    -    biggest2    -    biggest3    -    biggest4    -    biggest5      findBiggestNumber 1E5

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Find the largest number in a multidimensional array var max        for var i 0  arr length gt i  i           var arra   arr i      var largest   Math max apply Math  arra      max push largest     return max

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Run this   Array prototype max   function        return Math max apply  Math  this         And now try  3 10 2  max   returns 10

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I just started with JavaScript  but I think this method would be good  var array    34  23  57  983  198   var score   0   for var i   0  i   array length  i        if array  i    gt  score        score   array i

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Resig to the rescue   Array max   function  array        return Math max apply  Math  array         Warning  since the maximum number of arguments is as low as 65535 on some VMs  use a for loop if you re not certain the array is that small

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Using - Array prototype reduce   is cool    267  306  108  reduce  acc val   gt   acc gt val  acc val   where acc   accumulator and val   current value    x000D   x000D  var a    267  306  108  reduce  acc val   gt   acc gt val  acc val   x000D   x000D  console log a   x000D   x000D   x000D

[javascript] How might I find the largest number contained in a JavaScript array?

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