[JavaScript] 현재 가장 높은 수치의 z-index는?

!markdown

# JavaScript (자바스크립트)

### 1. 가장 높은 수치의 z-index 구하기 Function

```js

function findHighestZIndex(tagName){

    var highestIndex = 0;

    //Makes parameter array

    if (!tagName){

        tagName = ['div'];

    }else if (typeof tagName == 'string'){

        tagName = [tagName];

    }

    //Search

    if (tagName instanceof Array){        

        for (var i=0; i<tagName.length; i++){

            var elementList = document.getElementsByTagName(tagName[0]);            

            for (var i=0; i<elementList.length; i++){

                var zIndex = document.defaultView.getComputedStyle(elementList[i], null).getPropertyValue("z-index");

                if (zIndex > highestIndex && zIndex != 'auto'){

                    highestIndex = zIndex;

                }

            }    

        }    

    }else{

        console.log('Could not get highest z-index. because, not good parameter', tagName);

    }

    return parseInt(highestIndex);

}

```

### 2. Function 호출

```js

var hightestIndex = findHighestZIndex('div');

```

OR

```js

var hightestIndex = findHighestZIndex(['div', 'span', 'p']);

```

### 참고

How can you figure out the highest z-index in your document? : [http://stackoverflow.com/questions/1118198/how-can-you-figure-out-the-highest-z-index-in-your-document](http://stackoverflow.com/questions/1118198/how-can-you-figure-out-the-highest-z-index-in-your-document)