current position:Home>JS JavaScript how to get the subscript of a value in the array
JS JavaScript how to get the subscript of a value in the array
2021-08-21 19:46:42 【zdz8207】
js The subscript of a value in the array
javascript Know the value of an element in an array , How to get array subscripts
JS Get the subscript of an element of the array Function method
use prototype Prototype implementation , Find the index value of the element in the array
js Find the position of the element in the array (index value )
Traverse all arrays , When the value in the array is the same as the value you expect, just return the subscript .
/* * Get the subscript of an element * arr: The array passed in * obj: The element that needs to get the subscript * */ function getArrayIndex(arr, obj) { var i = arr.length; while (i--) { if (arr[i] === obj) { return i; } } return -1; } // use prototype Prototype implementation , Find the index value of the element in the array Array.prototype.getArrayIndex=function(obj){ for(var i=0;i<this.length;i++){ if(this[i]===obj){ return i; } } return -1; } var testarr = [1,2,3,4,5]; // obtain 2 stay testarr The subscript in is 1 testarr.getArrayIndex(2);
- 1.
- 2.
- 3.
- 4.
- 5.
- 6.
- 7.
- 8.
- 9.
- 10.
- 11.
- 12.
- 13.
- 14.
- 15.
- 16.
- 17.
- 18.
- 19.
- 20.
- 21.
- 22.
- 23.
- 24.
- 25.
- 26.
- 27.
// Method to get the next subscript index of an element var obj = 2;
var arrlist = [1,2,3,4,5]; var index = getArrayIndex(arrlist,obj); var to = index+1; if(to > arrlist.length){ to = arrlist.length-1; }
- 1.
- 2.
- 3.
- 4.
- 5.
- 6.
- 7.
- 8.
Expanding knowledge :
1, What is an array
An array is an ordered collection of values , Each value is called an element , And each element has a position in the array , In numbers , Known as the index .\
js The array of is typeless , Array elements can be of any type , Different elements in the same array may be objects or arrays .
The indexes of array elements do not have to be continuous , There can be gaps between elements , It's called a sparse array .
For example, sparse arrays var c = [1,,2]; The maximum index is 2, The array length is 3.
Each array has a length attribute . For non sparse arrays ,length Property is the number of array elements ,
For sparse arrays , Elemental length Attribute is larger than the index of all elements .
golang Technology exchange group :316397059,vuejs Technology exchange group :458915921 Infiltration technology :534096581, Money hoarders :621258209, You can join me if you are interested
WeChat official account : Nature predicts (ssqyuce) Heart Zen (xinchandao)
copyright notice
author[zdz8207],Please bring the original link to reprint, thank you.
https://en.qdmana.com/2021/08/20210821194639242Q.html
The sidebar is recommended
- Another ruthless character fell by 40000, which was "more beautiful" than Passat and maiteng, and didn't lose BMW
- CSS learning notes - Flex layout (Ruan Yifeng tutorial summary)
- Zheng Shuang's 30th birthday is deserted. Chen Jia has been sending blessings for ten years. Is it really just forgetting to make friends?
- Front end Engineering - scaffold
- Array de duplication problem solution - Nan recognition problem
- New choice for app development: building mobile applications using Vue native