In Javascript, we often need to manipulate array objects. This post mainly introduces: ① How to get the index of array elements? ② How to delete array elements? ③ How to slice array elements? ④ How to insert elements in the array? ⑤ How to concat arraies?
Keywords: Javascript , array , indexOf , delete , slice , insert.
IndexOf
Sometimes we need to get the index of an array element. In this case, we can use the indexOf() method. If no element is found, the function returns -1. It should be noted that if the array or object is stored in the array, the returned result of indexOf() will always be -1. It is necessary to compare the sub-objects in the elements one by one to see if they are equal to obtain the index. Or you can use JSON.stringify() methond to compare two object, but if the order of object key are need to be consistent, otherwise, you will always get False even compare two same object.
Delete
When deleting elements from an array, you can use the splice(start_index, count) function, where start_index indicates the position where the start index, and count indicates how many elements to delete from start_index.
Slice
Use slice(start_index, end_index) function when intercepting elements of an array.
Insert
To insert element in an array, you can use the unshift() or push() methods. The unshift() method inserts element at the beginning of array, and the push() method inserts element at the end.
Concat
If you want to concat two arraies, there are concat(), apply(), push() and for..loop methods.
In Javascript, we can use indexOf() to get element index,use splice() to remove element,use unshift() and push() to insert element, use concat(), apply() and for…loop to concatenate arrays.
