Element-wise operations of Arrays in Julia

How to compare elements in different arrays, and how to change elements based on the comparison

a = [1 2];

b = [10 -10];

a[a .> 1]

> [0 1] # [false true]

a[a .> 1] = 100;

# a is now [1 100]

b[a .> 1] = 0;

# b is now [10 100]