1, access to DOM elements
document.getElementById ( "ID"): Get all the elements in the document ID, the prerequisite is to have an ID tag
document.getElementByTagName ( "Tag"): Gets Tag label (like li, ul, div, etc.) at all elements of the return value is an array, there is no style attributes
When the two mix, document.getElementById ( "ID"). GetElementByTagName ( "Tag"), note that the second document would not increase, because it is the first look at the premise of the second element
2. Set the style DOM element
DOM value .style.styleName = "styleValue": Note styleName not have a separator , is an array of elements, must be traversed to become a single element to set the style, the style must be provided prior to the acquired element