What does this ^ mean in the following code line:  
tr[class^="row"]
In the HTML how does it looks like? if used:
var rows = document.querySelectorAll('tr[class^="row"]');
What does this ^ mean in the following code line:  
tr[class^="row"]
In the HTML how does it looks like? if used:
var rows = document.querySelectorAll('tr[class^="row"]');
In a css selector, ^= means "begins with"
Please see MDN - Attribute Selectors for more information.