To get the length of a java script object : If I have a JavaScript object, say

    data
    :
    Array[1]
    0
    :
    Object
    section
    :
    Array[6]
    tool
    :
    Array[6]
    wellcon
    :
    Array[6]
    welltra
    Array[6]
from this how i get the section length.
i try like

 data.section.length but this is wrong. 
what is the wrong in my syntax?