JS Learning Note One

JS Basic knowledge:

1.JavaScript: Change HTML content

Instance

X=document.getelementbyid ("demo")  //Find element x.innerhtml= "Hello JavaScript";    Change Content

<script>
function MyFunction ()
{
X=document.getelementbyid ("demo"); Find element
X.innerhtml= "Hello javascript!"; Change Content
}
</script>

<button type= "button" onclick= "MyFunction ()" > click here </button>

2.JavaScript: Change HTML style

Instance

X=document.getelementbyid ("demo")  //Find element x.style.color= "#ff0000";           Change Style

<script>
function MyFunction ()
{
X=document.getelementbyid ("demo")//Find element
X.style.color= "#ff0000"; Change Style
}
</script>

<button type= "button" onclick= "MyFunction ()" > click here </button>

3.JavaScript: Validate input

Instance

If IsNaN (x) {alert ("Not Numeric")};

<script>
function MyFunction ()
{
var X=document.getelementbyid ("Demo"). Value;
if (x== "" | | IsNaN (x))
{
Alert ("Not Numeric");
}
}
</script>

<button type= "button" onclick= "MyFunction ()" > click here </button>

4.JavaScript: Change HTML image
Tap the light bulb to turn the lamp on or off
<script>
function changeimage ()
{
Element=document.getelementbyid (' myimage ')
if (Element.src.match ("Bulbon"))
  {
element.src= "/i/eg_bulboff.gif";
  }
Else
  {
element.src= "/i/eg_bulbon.gif";
  }
}
</script>

 /i/eg_bulboff.gif" >

 5. The function is called when the button is clicked
<Script>functionmyFunction () {document.getElementById ("Demo"). InnerHTML="My First JavaScript Function";}</Script> <Buttontype= "button"onclick= "myFunction ()">Try it</Button>

JS Learning Note One