Classify array methods by method properties

A method that changes the array itself

Three common methods:
  • splice(startIndex, deleteCount, ... items)— Adds an element from the specified location, returns the deleted element (returns an empty array when added).
  • sort(func(a,b))— Array sort,Sort by character encoding order. The time complexity depends on how the browser is implemented.
  • reverse()Reverse array, equivalent in Google /Microsoft Edgesort((a,b)=>-1), the equivalent in Firefoxsort((a,b)=>1).
Add and delete (queue, stack implementation) method:
  • push(... items)Add elements from the tail. Returns the array length after push.
  • pop()— Remove the tail element. Returns a tail element (not an array).
  • unshift(... items)Add elements from the header. Returns the array length after unshift.
  • shift()— Remove the header element. Returns the header element (not an array).
Treatment methods:
  • fill(value,start,end)— Fill the start index with value to end, excluding end.
  • copyWithin(targetIndex,start,end)— Copy and replace elements from start to end(optional) after targetIndex. The length of the array remains the same.

Methods that do not affect the original array

Adding and deleting methods:
  • slice(start,end)— shallow copy from ‘start’ index to ‘end’ index and return.
  • concat(... items)Merge the parameter elements into the array. If the argument is an array, the element is taken.
Query method:
  • indexOf(item)— Query the specified element index without returning -1.
  • lastIndexOf(item,start)— Query the last position of the specified element. ‘start’ specifies the starting position of the query, optional.
  • includes(item)Return true if the array contains the element, false otherwise.
  • find(func(item, index, arr))— Returns one that satisfies the func() conditionThe first element.
  • filter(func(item, index, arr))— Returns the func() conditionAll elements (array).
  • findeIndex(func(item, index, arr))— Returns one that satisfies the func() conditionThe first element index value.
Treatment methods:
  • map(func(item, index, arr))Returns a new array of elements returned by func.
  • split(str,len)Method of String that returns a split array of STR. STR: delimiter/regular expression, len returns the specified length of the array.
  • join(str)Insert STR between array elements to return the concatenated string. When no arguments are passed, elements are concatenated with commas.
  • reduce(func(acc,item,index,arr),initialValue)Returns the final iteration of the func processed array. Acc: result of last iteration; Item: current value (Let’s start with the second element); Index: index of the current executing element (Starting from 1), arR: original array, initialValue: initial ACC value of the first call to funC.
  • reduceRight(func(acc,item,index,arr),initialValue)— Equivalent to reduce(),func executes from the right.
  • forEach(func(item, index, arr))— Traverses the number group, no return value.
  • isArray(arr)— Checks whether arR is an array and returns a Boolean value.
Other:
  • from(arrlike,func(item),this)Generates a new shallow-copy array from the class array object.
  • of(... items)Generates an array from the parameters passed in.
  • entries()Returns a new array iterator containing the key-value pairs for each index.
  • keys()– return byThe index keyConstitute an iterable.
  • values()– return byThe value of each indexConstitute an iterable.
  • every(func(item,index,arr),this)Whether or not –All elements satisfyFunc condition that returns a Boolean value true.
  • some(func(item,index,arr),this)—As long as there are elements that satisfyFunc condition that returns a Boolean value true.
  • flat(depth)Depth reduces the array to the specified depth, and returns a new array.
  • flatMap()— Equivalent to the flat() function at depth 1 after the map traverses the array.
  • toString()Returns a string of elements concatenated by commas.
  • toLocaleString(locales,options)Returns a string of elements concatenated by commas. (Locale can be specified)