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This is a summary of some of the most common methods used in JavaScript arrays, classified by adding, deleting, and such purposes. It covers most of the everyday development scenarios.

increase

Push – Tail-add

Add one or more elements to the end, returning the new length of the array.

Unshift – Header added

Adds one or more elements to the header and returns the new length of the array.

delete

Pop – Tail deletion

Removes an element from the tail and returns the element.

Shift – Head removed

Removes an element from the header and returns the element.

change

Splice – Add Replace delete

Add, remove, and replace elements. It’s going to change the array.

arrayObject.splice(index,howmany,item1,..... ,itemX)Copy the code

check

Find – Find by function

Find the first element that satisfies the condition of the detection function and return that element, or undefined if not found.

FindIndex – Search by function

The first element that satisfies the condition of the detection function is found and the index of that element is returned. Cannot find return -1.

IndexOf – Searches by element value

Finds the element and returns the element index.

Cannot find return -1

The second parameter indicates the starting position of the search

LastIndexOf – Finds by element value

Look for elements from back to front and return the element index. If not found, return -1.

The second parameter indicates the starting position of the search

The sorting

Sort sort –

Sort the elements of an array. Note that the array is sorted on top of the original array. No copies are made.

If this method is called without arguments, the elements in the array are sorted alphabetically or, more precisely, by character encoding.

If you want to sort by other criteria, you need to provide a comparison function.

Reverse order

Invert the array and return the new array. It’s going to change the array.

merge

Join – Join into a string

Merges all elements of the array into a string and returns.

Concat – Merges into an array

Combine two or more arrays to return a completely new array.

traverse

forEach

Iterates over the elements in the array and executes the callback function.

array.forEach(function(currentValue, index, arr), thisValue)
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Example:

let arr = ['a','b','c']
arr.forEach(function(currentValue, index, arr){
    console.log('currentValue',currentValue)
    console.log('index',index)
    console.log('arr',arr)
})
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detection

The value includes detection

Determines whether the string contains the specified substring. Return true if a matching string is found, false otherwise.

string.includes(searchvalue, start)
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Find if the string contains Axjy

Look up from the sixth index position

Some – Functions contain checks

Detecting whether there are elements in the array can be verified by the detection function, which executes each element of the array in turn.

  • If one of the elements satisfies the condition, the expression returns true, and the remaining elements are not tested
  • If there are no elements that satisfy the condition, false is returned.
array.some(function(currentValue,index,arr),thisValue)
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Every – The function is fully detected

Check whether all elements in the array can be validated by the check function.

  • If one element in the array is detected as unsatisfactory, the entire expression returns false and the remaining elements are not tested.
  • Returns true if all elements meet the criteria.
array.every(function(currentValue,index,arr), thisValue)
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other

Filter – The filter function

Creates a new array by checking all the elements in the specified array that meet the criteria. It doesn’t change the original array.

array.filter(function(currentValue,index,arr), thisValue)
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Slice – slice an array

The begin and end parameters are used to cut the array without changing the original array.

Map – map

Returns a new array whose elements are the values of the original array elements.

array.map(function(currentValue,index,arr), thisValue)
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Returns an array with twice as many elements as the original array.

CopyWithin – Internal copy

Use to copy elements from a specified position in an array to another specified position in the array without changing the original array length.

array.copyWithin(target, start, end)
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Copies the first two elements of the array onto the next two.

Fill – fills the function

Replaces the elements of an array with a fixed value.

array.fill(value, start, end)
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Fill the array with fixed values

Batch replace the specified location

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