key Memory ( routines ):
1. Key words: (must start with a letter, underscore (_), or dollar sign ($), identifier , variable (is a name, preferably preceded by a letter, is case-sensitive), constant (is a value with a data type)
Variable:
① Define and assign values
② use
2. Data type: numeric string boolean null undefined object
data type conversions: Alert (typeof information); //Determine the data type of the information
Other type-to-string: Global method String () //string (123)
Number, Boolean available tostring () //(ture). ToString
String to number:parsefloat//Recommended Use
parseint (AA)//will take the whole
Number (AA)//decimal operation will be problematic
3. Operators:
arithmetic operators:+-*/+ + (self-increase)-(self-subtract)% remainder
Self-increment and self-subtraction:
Only when you have a relationship with yourself, in front of no difference;
When participating in an expression: before //increment and re-operation in the back //first operation and then self-increment
assignment Operator:= + = = *=/=
+ =: A + = 2 ==> a = a+2;
relational operators:< > <= >=! = = = = = = = =
= =: Comparison value
= = = Comparison Value and type
Logical operators:
&&(with): Both sides are true, the result is true;
|| (OR) : as long as one side is true, the result is true;
! (non):! True=false;
Ternary operators: //Handling simple (not true) judgments
An expression? Really do this: fake this;
4. Control statements
for--code Example:
var dy= ""; for (var i=1;i<10;i++) { for (var j=1;j<=i;j++) { dy =dy+j+ "*" +i+ "=" +i*j+ " " ; } Dy=dy+ "<br/>"; } document.getElementById ("Dayin"). Innerhtml=dy;
For loop print multiplication table
if--code example:
// title: 50 kg below 0.13 yuan per kilogram, exceeding the portion per kilogram of 0.2 yuan // Assign the weight of the baggage entered to W var w = prompt ("Enter your baggage weight (KG)"), y; // calculate freight According to the weight entered if (w <=) { = w * 0.13;} Else { // Primitive: 50*1.3+ (w-50) *0.2; y = w * 0.2-3.5;} // The output Freight alert ("You need to pay the shipping cost is" +y+ "Yuan");
Shipping Issues
switch--code Example:
Scissors Games: 0-Scissors 1-Fist 2-cloth//Assign the number you entered to youvaryou = prompt ("Please enter the 0/1/2 you want out of");//assign a computer's random number to a PCvarPC = parseint (Math.random () * 3);//alert ("Computer out of the number is" +pc);//judging the winning and losing according to the boxing situationSwitch(You) { Case"0": Switch(PC) { Case0: Alert ("A very close"); Break; Case1: Alert ("You lost."); Break; Case2: Alert ("You won."); Break; default: Break; } Break; Case"1": Switch(PC) { Case0: Alert ("You won."); Break; Case1: Alert ("A very close"); Break; Case2: Alert ("You lost."); Break; default: Break; } Break; Case"2": Switch(PC) { Case0: Alert ("You lost."); Break; Case1: Alert ("You won."); Break; Case2: Alert ("A very close"); Break; default: Break; } Break; default: Break;}
Scissors Mini Games
Array
Method (function)
A class is a set of commonalities.
An object is an XX in the collection and can have its attributes.
0317-JS variable data type operator control statement