Question

Can anyone tell me why in the following code a do/while lop is used rather than a simple if statement:

function prev(elem){
do {
    elem = elem.previousSibling;
} while(elem && elem.nodeType != 1);
    return elem;
}

Why not:

function prev(elem){
if(elem && elem.nodeType != 1) {
    elem = elem.previousSibling;
    return elem;
}

Is there an advantage to using do/while? Thanks!

Answer 1

do-while will run once and continue running while the statement is true, while the if-statement will only run once.

In this instance it may be equivalent (depending on how the code and data is set up), but typically that is how do-whiles are used.