What difference does the space make.

Example 1: Without a space only divs of class 'class' will be selected.

//divs with class class

Second Example: The space will select all elements with class 'class' that are children of divs.

//all children, level irrelevant
$('div .class')

Third Example: Select direct children wich class class only.

//direct children only
$('div > .class')