Can someone explain this code line to me?

Discussion in 'Javascript' started by effendi@epitome.com.sg, Apr 3, 2005.

  1. Guest

    Hi everyone, I am relatively new to JS and I am hoping someone could
    tell me what this line of codes mean. This was written by some
    brilliant guys at webfx and I am trying to understand some of their
    codes.

    To begin with I don't understand how this variable is set.

    var sliderE1=document.getElementByID?
    document.getElementById("slider-1"): null;

    Question 1: What is the function of the "?" mark after the
    document.getElementByID
    Question 2: What is the reason for including ": null"
    and Question 3: Can't this be done just by simply using
    "document.getElementById("slider-1")"?

    Thanks in advance.
    , Apr 3, 2005
    #1
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  2. Evertjan. Guest

    wrote on 03 apr 2005 in comp.lang.javascript:

    > Hi everyone, I am relatively new to JS and I am hoping someone could
    > tell me what this line of codes mean. This was written by some
    > brilliant guys at webfx and I am trying to understand some of their
    > codes.
    >
    > To begin with I don't understand how this variable is set.
    >
    > var sliderE1=document.getElementByID?
    > document.getElementById("slider-1"): null;
    >
    > Question 1: What is the function of the "?" mark after the
    > document.getElementByID
    > Question 2: What is the reason for including ": null"


    var condition = false
    var a = (condition) ? "This is true" : "This however is false"
    alert(a)

    will show: This however is false

    var condition = true
    var a = (condition) ? "This is true" : "This however is false"
    alert(a)

    will show: This is true

    =========================================

    > and Question 3: Can't this be done just by simply using
    > "document.getElementById("slider-1")"?


    (document.getElementByID)

    is only true in browsers that support it.
    in other [read older] browsers:

    var sliderE1 = document.getElementById("slider-1")

    would give an error and the js would stop.

    ========================================

    Your first questions are so basic,
    that I suppose you did not read any javascript tutorial before asking.

    <http://www.google.com/search?q=javascript.tutorial>

    --
    Evertjan.
    The Netherlands.
    (Replace all crosses with dots in my emailaddress)
    Evertjan., Apr 3, 2005
    #2
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