Calling two javascript function on a single click

When you return the result of your first function the block is exited. Unless you're going to do something with the result, you should say:

<a href="#" onClick="return firstFunction() ? secondFunction() : false;">Click me</a>

You currently have:

function () {
    return firstFunction();
    secondFunction();
}

This calls firstFunction then returns its value, and never reaches the call to secondFunction.

You want:

function () {
    var result = firstFunction();
    if (result) {
        secondFunction();
    }
}

<a href="#" onClick="foo()"> Click me </a>

function foo(){
    if (firstFunction() === true)
        secondFunction()
}

return exit the function so you just returned firstFunction and exited the function, like

function foo(){
    return firstFunction();
     secondFunction(); // Unreachable code.
}

<a href="#" onClick="return if (firstFunction()) secondFunction();"> Click me </a>

if you want true to mean "only true and not just something that = true using a boolean comparison"

<a href="#" onClick="return if (firstFunction()===true) secondFunction();"> Click me </a>

but you probably don't