Shulou(Shulou.com)06/01 Report--

Array 1. Basic method

1) Array.prototype.unshift (item1,item2,item3...)

Description: add elements to the front of the array. You can pass in more than one parameter at a time. Note: elements are added to the front of the array in the order currently passed in.

Example: var arr = ['axiajiajiaozhuo']

Var result = arr.unshift (9)

Console.log (result) / / 4console.log (arr) / / [9 var result1 = arr.unshift (9)

Console.log (result1) / / 6console.log (arr) / / [9, 8, 9, 9, 9, 8, 9, 9, 9, 8, 9, 9, 9, 9, 8, 9, 9, 9, 5, 9, 9, 9, 9, 9, 8, 9, 9, 9, 9, 9, 9, 8, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 8, 9, 9, 9, 9, 9, 9, 9, 8, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 8, 9, 9, 9, 9, 9, 9, 8, 9, 9, 9, 9, 9, 9, 8, 9, 9, 9, 9, 9, 8, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9

Analysis: 1, the method will change the original array 2, the method itself will return the length of the new array 3, the second time is after the first addition of elements before the operation, so will retain the results of the first operation, to avoid ambiguity, the following operations are the same.

2) Array.prototype.push (item1,item2,item3...)

Description: add elements to the end of the array, passing in more than one parameter at a time; elements are added to the end of the array in the order currently passed in.

Example: var arr = ['axiajiajiaozhuo']

Var result = arr.push (9)

Console.log (result) / / 4console.log (arr) / / [var result1 = arr.push (9L8)

Console.log (result1) / / 6console.log (arr) / / ['axiajiaoyuanzhongyuanjingyuanzhangyuanzhongyuanzhongyuanzhongyuanzhongyuanzhongyuanzhongyuanqingzhongyuanzhongyuanzhongyuanzhongyuanzhongyuanzhongyuanzhongyuanqingzhongyuanqingzhengjiaojie 8]

Analysis: 1. The method will change the original array 2, and the method itself will return the length of the new array.

3) Array.prototype.shift ()

Description: delete the element with index 0 in the array and do not accept passing parameters (passing parameters will be ignored)

Example: var arr = ['axiajiajiaozhuo']

Var result = arr.shift ()

Console.log (result) / / 'a'console.log (arr) / / [' baked dharma c']

Analysis: 1. The method will change the original array; 2, the method itself will return the deleted element (note that it is the element, not the index ~); 3. If the array is empty, the method itself will return undefined

4) Array.prototype.pop ()

Description: delete the last element in the array and do not accept passing parameters (passing parameters will be ignored)

Example: var arr = ['axiajiajiaozhuo']

Var result = arr.pop ()

Console.log (result) / / 'c'console.log (arr) / / [' axiomagol']

Analysis: 1, the method will change the original array; 2, the method itself will return deleted elements; 3, if the array is empty, the method itself will return undefined `

two。 Conversion method

1) Array.prototype.toString ()

Description: converts an array to a string, concatenated by a comma.

Example: var arr = ['axiajiajiaozhuo']

Var result = arr.toString ()

Console.log (result) / / 'arecinct brecedomain console.log (arr) / / ['axiajiaoyuanjiaoyuanjia']

Analysis: 1. This method does not change the original array 2. This method returns array elements in the form of strings connected by commas.

2) Array.prototype.join ()

Description: convert the array to a string, concatenated with the passed parameters; Note: when multiple parameters are passed, only the first parameter is selected. If no parameters are passed, they are connected by comma by default.

Example: var arr = ['axiajiajiaozhuo']

Var result = arr.join ('-')

Console.log (result) / / 'a-b-c'console.log (arr) / / [' axiajiaoyuanzhongyuanshou]

Analysis: 1. This method does not change the original array. 2. This method returns array elements in the form of strings connected by the passed parameters.`

3. Operation method

1) Array.prototype.concat ()

Description: join two arrays, and you can also pass elements directly. If you don't pass parameters, you can copy the array.

Example: var arr = ['axiajiajiaozhuo']

Var result = arr.concat ([1Jue 2])

Console.log (result) / / [] the array passed in is added to the end of the element by default console.log (arr) / / ['axiaojiaozhuangjiaoc'] does not change the original array var result = arr.concat (1jue 2).

Console.log (result) / / [console.log (arr) / / [var result = arr.concat ()] can input elements directly and interval them with commas.

Console.log (result) / ['axiajiaojiao']

Console.log (arr) / / [console.log (result) / / a pair of result operations console.log (result) / / ['axiaqunzhub'] console.log (arr) / / [' axiaojiaozhuangc'] result deletes an element and does not affect arr, so using the concat () method returns a new array without changing the original array

2) Array.prototype.slice (start,end)

Description: intercept string fragments. Both start and end are index values. The intercepted element range [start,end) contains start, does not contain end, and does not change the original array.

Example: var arr = ['axiajiajiaozhuo']

1. If no parameter is passed, the entire array will be intercepted by default and the new array var result = arr.slice () will be returned.

Console.log (result) / / [arr) / / [console.log (arr) / /] 2. If a parameter is passed, it means that the last element of the array, var result = arr.slice (2), is intercepted from the current parameter index.

Console.log (result) / / ['c'] console.log (arr) / / [a negative number indicates the reciprocal position of the number in the array and is intercepted to the last element of the array var result = arr.slice (- 2).

Console.log (result) / / [console.log (arr) / / ['axiomagadence]] 4. Pass two parameters (if the start parameter is greater than the end parameter, an empty array will be returned) var result = arr.slice (1Pol 2)

Console.log (result) / / ['b'] console.log (arr) / / ['aqiao] 5. Pass two parameters. If the former is positive and the latter is negative, the index of the former element starts and is truncated to the position of the reciprocal negative number, excluding the value of the current negative position (if the element of the first value index happens to be the position of the second value). An empty array will be returned) var result = arr.slice (1mai Murray 1)

Console.log (result) / / ['b'] console.log (arr) / / ['axiajiaozhuo']

3) Array.prototype.splice (start,len,item,item...)

Description: delete the fragment, start indicates the start of the index, len indicates the length of the deletion, item is an optional parameter, the TOEFL training institution indicates the element inserted after deletion, the change method will return the deleted element and change the original array

Example: var arr = ['axiajiajiaozhuo']

1. If no parameter is passed, it will not be deleted. Empty array 2 will be returned. If a parameter is passed, it will be deleted to the last element var result = arr.splice (1) starting from the position of the current parameter index.

Console.log (result) / / ['baked dint'] console.log (arr) / / ['a'] 3. If a parameter is passed and it is negative, it will be deleted to the last element var result = arr.splice (- 1).

Console.log (result) / / ['c'] console.log (arr) / / ['axiomanagemb'] 4. If I is negative, an empty array will be returned, which means that if there is no operation 5 or three or more parameters are passed, it will be inserted into the position of the deleted element var result = arr.splice starting from the third element.

Console.log (result) / / ["b"] console.log (arr) / / ["a", 4, 4, "c"]

4. Location method

1) Array.prototype.indexOf (item1,item2)

Description: item1 represents the element to be found, item2 represents the starting index value of the search, and returns the index value of the element found

Example: var arr = ['axiajiajiaoyuanzhongyuanzhongyuanzhongyuanzhongyuanzhongyuanzhongyuanshou

1. Stop searching when you find it, even if it is followed by this element var result = arr.indexOf ('astatine 0)

Console.log (result) / / 0console.log (arr) / / ['axiajiaoyun'] 2. If it is not found, it will return-1var result = arr.indexOf ('dcurire0).

Console.log (result) / /-1console.log (arr) / /] 3. If item2 does not pass parameters, var result = arr.indexOf ('a') will be found from the location with index 0 by default.

Console.log (result) / / 0console.log (arr) / / ['axiaqiaoyun'] 4. If item2 passes a negative number, look for var result = arr.indexOf from the position of the reciprocal to the back of the array.

Console.log (result) / / 3console.log (arr) / / ['axiajiaozhuo']

2) Array.prototype.lastIndexOf (item1,item2)

Description: just like indexOf, except looking from back to front

5. Sorting method

1) Array.prototype.reverse ()

Description: flip the array, change the original array, do not accept parameters (as long as it does not pass illegal values, it will not affect its function)

Example: var arr = ['axiajiajiaozhuo']

Var result = arr.reverse ()

Console.log (result) / / [] console.log (arr) / / ['cedars,']

2) Array.prototype.sort ()

Description: array sorting, default from small to large, change the original array

Example: var arr = ['axiaxiajiaozhuangyuanzhongyuanzhongyuanzhongyuanzhongyuanzhongyuanzhongyuanfangzhongyuanzhongyuanzhongyuanzhongyuanzhongyuanzhongyuanzhongyuanzhongyuanzhongyuanzhongyuanzhongyuanqingzhongyuanzhongyuanqiao [' axiaxiajiaozhong, bangzhongjiaozhuo]

1. Numeric precedence letter var result = arr.sort ()

Console.log (result) / / [1,2, "a", "b", "c"] console.log (arr) / / [1,2, "a", "b", "c"] 2, sort the words by the first letter, compare the second letter if the first letter is the same, and so on var arr = ['ba','ce','bb','aa'] var result = arr.sort ()

Console.log (result) / / ["aa", "ba", "bb", "ce"] console.log (arr) / / ["aa", "ba", "bb", "ce"] 3, multi-digit sort, also starting from the first bit, if the same is compared with the second bit, and so on var arr = ['33'] var result = arr.sort ()

Console.log (result) / / ["1", "123," 33 "] console.log (arr) / / [" 1 "," 123, "33"] if you really want to achieve size sorting, this method accepts fixed parameters, Array.prototype.sort (function (areline b) {return Amurb}).

The order of the formal parameters is: a return bregory return a ray b means an ascending order, and a b ray a means a descending order var arr = ['33'a'] var result = arr.sort (function (a moment b) {return a ray b})

Console.log (result) / / ["1", "33", "123"] console.log (arr) / / ["1", "33", "123"]

String attribute and method character method

Note: the string is immutable, so none of its methods will change the string itself = =

1) String.length

Description: represents the character length of a string

2) str []

Description: you can get the characters at the specified position and count them from 0

3) String.prototype.charAt ()

Description: gets the characters at the specified location

Example:

Str = 'num'

Console.log (str.charAt (1))

4) String.prototype.charCodeAt ()

Description: gets the ASCII code of the specified position character

Example:

Str = 'num'

Console.log (str.charCodeAt (1))

Operation method

1) String.prototype.concat ()

Description: connect the string, but generally not, because a + can solve ~

Example: var str = 'num' console.log (str.concat (' cv')) / / 'numcv'

2) String.prototype.slice (start,end)

Like the array, I won't repeat it here.

3) String.prototype.substring (start,end)

Basically the same as slice, it is generally fine to use slice

4) String.prototype.substr (start,len)

Similar to splice, intercepting clips

Replacement method

1) String.prototype.replace (value,rep)

Description: replace the element in the string and return the replaced string, only the first element found will be replaced, even if there is the same element later (error will be reported if you pass multiple parameters)

Example: var str = 'numnnnn'

Console.log (str.replace ('nasty gramma') / / 'aumnnnn'console.log (str.replace (' n')) / / 'undefinedumnnnn' only passes an element that will be replaced by undefined to find the element`

Location method

1) String.prototype.replace (value,rep)

2) String.prototype.replace (value,rep)

Case conversion

1) String.prototype.toUpperCase ()

Returns a new string converted to uppercase letters

2) String.prototype.toUpperCase ()

Returns a new string converted to lowercase letters

Remove spaces

1) String.prototype.trim ()

Remove the spaces before and after the string

Conversion mode

1) String.prototype.split (item,limit)

Description: take the parameter number string as the boundary, split the string and return an array item can be a string or a regular expression limit an integer to limit the number of segments returned

Example: var str = 'nuamnannan' console.log (str.split (' a')) / / ["nu", "mn", "nn", "n"]

Str = 'nuamnannan''a',2))

Finally finished, but really tired ah, later forgot to read their own article, do not know when to praise or despise their own QAQ

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