Javascript-an interactive javascript tutorial

Javascript-an interactive javascript tutorial
This site also provides some other languages for you to learn. Playing in this interactive mode is much more impressive than reading a book. Record a point: the usage of javascript substring is somewhat interesting. To take the four characters "12345678" in "4567", use "12345678". substring ). Here, start is based on 0, which is nothing special, but end seems to be based on 1 (shouldn't it be up to 6th characters? Why 7th ?), It is inconsistent with the general thinking. In my opinion, the correct understanding of this method should be that all characters between the first few intervals and the first few intervals. Suppose there is a cursor "|" scanning from the left side of the 3rd characters, always scanning to the left side of the 7th characters cursor position (0 base ).