How to get JavaScript value in PHP?

Javascript: Get previous array element value?

• I'm trying to do this col[i] = childWidth + col[i-1]; To get the previous array item value, but the output I get for this just says NaN. It works fine when I don't have the -1 in the array brackets. How do I get the previous value?

• Answer:

  It's hard to say unless you post previous lines but my guess would be childWidth is a number and col[i-1] is undefined. are all elements of your array col defined? Edit: OK, your loop is not posted fully, but assuming you're doing it correctly for(var i = 1; i < some_number; i++) and the line posted in your original post was inside the loop, childWidth should be undefined. Make sure you've defined it somewhere before col[i] = childWidth + col[i-1]; possibly before the loop.