javascript common codes

Javascript embedded

Comments

//or /*content*/

Variable name assignment

Var Variable name = value

Output method

Document .write(variable name )

window.alert(variable name)

arithmetic operator

a++;a--

assignment operator

string operator

comparison operator

Ternary Operator

Format: Expression? Value 1: Value 2

For example: (a>b? a:b)

Logical operator

Logical AND: && It requires that the results of both sides of && must be true to be true

Logical OR: | | It requires that only one of the two sides of || is true

logical negation:! Negation Turn true into false and false into true

If statement

Single branch

Format: if(conditional expression){ //Statement block }

Multi-branch

Format: if(conditional expression){ //Statement block }else{ //Statement block }else{ //Statement block }

For loop

for(var Variable initialization; conditional expression; variable update) { // Loop body }

Loop interruption-break

After reaching the break keyword, the entire loop will be interrupted and the loop will not continue to execute!

User input dialog box

Format: window.prompt(text,defaultText)

text: Prompt information Optional

defaultText: Optional Default displayed data

Definition array

Format 1: var variable name = [array element 1, array element 2]

format 2: var variable name = new Array (array element 1, array element 2);

traverse the array

format: var variable name = [array Element 1, array element 2]

for(var i=1;arr[i]

arr[i]

}

Multidimensional array

Format: array variable name[ Subscript of one-dimensional array][Subscript of two-dimensional array element];

Define function

Format: function function name (parameter 1, parameter 2, parameter n) { // function body }

Calling a function

Format: function name ()

Return keyword

return means "return"!

return is written in the function body!

The return keyword has two meanings

Self-calling of anonymous functions

Format: (function(){})()