Re question (1):

Most FFTs, or the way atan2() is commonly used with complex FFT results to compute a phase, produce a zero phase (strictly real) output for strictly symmetric input.  This means you want cosine waves, periodic in aperture, not sine waves starting at zero at the window edge, for FFT results with zero phase.

matlab fft phase response square wave
I want to replace 

&lt;div class="blog"&gt;Blog&lt;/h1&gt;


with

&lt;h1&gt;Blog&lt;/h1&gt;


which is inside a class name "sidebar"

I used this code but didn't work:

$(window).load(function() {
    $( ".sidebar h1" ).replaceWith( "&lt;div class="blog"&gt;Blog&lt;/h1&gt;" );
}


What is wrong on my code?
