JS array with an existing array to create a new array

The concat () and Splice () methods allow new arrays to be created from existing arrays

Concat () This method can combine multiple arrays to create an array

Splice () This method is to get a subset of the truncated array to create a new array.

Theory: said are difficult to understand, directly on the code, practice, paper on the end of light.

　　　　　　

Splice (3,3) The parameter in this method means that the first parameter is the starting position of the intercept, and the second is the length of the Intercept.
JS array with an existing array to create a new array