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One, operator
(1) Arithmetic: + Plus, minus, * multiply,/divide,% take surplus
Example: Interlaced color, seconds turn time
<! DOCTYPE HTML PUBLIC "-//W3C//DTD XHTML 1.0 transitional//en" "Http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd ">
<meta http-equiv= "Content-type" content= "text/html; Charset=utf-8 "/>
<title> Interlaced </title>
<script>
Window.onload = function ()
{
var ali=document.getelementsbytagname (' Li ');
for (Var i=0;i<ali.length;i++)
{
if (i%2==0)
{
Ali[i].style.background= ' #CCC ';
}
Else
{
Ali[i].style.background= ";
}
}
};
</script>
<body>
<ul>
<li></li>
<li></li>
<li></li>
<li></li>
<li></li>
<li></li>
<li></li>
<li></li>
</ul>
</body>
<! DOCTYPE HTML PUBLIC "-//W3C//DTD XHTML 1.0 transitional//en" "Http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd ">
<meta http-equiv= "Content-type" content= "text/html; Charset=utf-8 "/>
<title> sec-Turn time </title>
<script>
var s=156;
Alert (parseint (S/60) + ' +s%60+ ' seconds ');
</script>
<body>
</body>
(2) Assignment Value: =, + =,-=, *=,/=,%=
Like what
i=i+1;
i++;
I+=1;
i=i+3;
i+=3;
(3) Relationship:<, >, <=, >=, = =, = =,! = (unequal),!==
(4) Logic:&& with, | | Or! Whether
Example: Full selection and inverse selection
(5) Arithmetic priority: parentheses
Second, the program flow control
(1) Judgment: If,switch,?:
Switch syntax:
Switch (variable)
{
Case value 1:
Statement 1;
Break
Case Value 2:
Statement 2;
Break
......
Default
Statement N;
}
?: syntax-ternary operator/three-mesh operator
In the IF syntax
if (condition)
{
Statement 1;
}else
{
Statement 2;
}
Equivalent to in the?: Grammar
Condition? Statement 1: Statement 2
(2) Cycle: While,for
(3) Jump: break,continue
<! DOCTYPE HTML PUBLIC "-//W3C//DTD XHTML 1.0 transitional//en" "Http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd ">
<meta http-equiv= "Content-type" content= "text/html; Charset=utf-8 "/>
<title>break and Continue</title>
<script>
for (i=0;i<5;i++)
{
if (i==2)
{
break;//Cycle Interrupt
}
alert (i);
}
</script>
<body>
</body>
<! DOCTYPE HTML PUBLIC "-//W3C//DTD XHTML 1.0 transitional//en" "Http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd ">
<meta http-equiv= "Content-type" content= "text/html; Charset=utf-8 "/>
<title>break and Continue</title>
<script>
for (i=0;i<5;i++)
{
if (i==2)
{
break;//Cycle Interrupt
continue;//just interrupted this cycle.
}
alert (i);
}
</script>
<body>
</body>
Iii. what is true and what is False
True: true, not 0 digits, non-empty strings, non-empty objects (such as document, array)
False: False, number 0, empty string, empty object (null), undefined
Four, Json
What is JSON: a subset of JavaScript-based.
<! DOCTYPE HTML PUBLIC "-//W3C//DTD XHTML 1.0 transitional//en" "Http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd ">
<meta http-equiv= "Content-type" content= "text/html; Charset=utf-8 "/>
<title>Json</title>
<script>
/*var a=12;
var b=5;
var c= ' abc '; */
var json={a:12, B:5, C: ' abc '};
alert (JSON.A);
json.b++;
alert (JSON.B);
</script>
<body>
</body>
(2) JSON and array
Loops: In general, arrays are used from 0-length loop statements
Encountered JSON with for in
<! DOCTYPE HTML PUBLIC "-//W3C//DTD XHTML 1.0 transitional//en" "Http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd ">
<meta http-equiv= "Content-type" content= "text/html; Charset=utf-8 "/>
<title>json and Arrays </title>
<script>
var json={a:12, B:5, c:7};
var arr=[12,5,7];
alert (JSON.A);
Alert (json[' a ']);//jons's subscript is a string
Alert (arr[0]);//The subscript of an array is a number
alert (arr.length);//Output 3
alert (json.length);//output Undefined,json no length
Cycle
/*for (Var i=0;i<arr.length;i++)
{
Alert (' +i+ ' element: ' +arr[i]);
}*/
/*for (var i in arr)
{
Alert (' +i+ ' element: ' +arr[i]);
}*/
for (var i in JSON)
{
Alert (' +i+ ' element: ' +json[i]);
}
</script>
<body>
</body>
"JS learning" JS Basic 2
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