JavaScript

Unfold Hierarchy number Tags Values

1 Examples

1.1 Variable

1.1.1 string

var stringA = "hello";
stringA += " world";
"Contains e:" + (stringA.indexOf("e") >= 0) + "   length:" + stringA.length

1.1.2 date

"current time: " + new Date() + "\n" + 
"format yyyy/mm/dd: " + new Date('2022/11/30 10:35:32') + "\n" + 
"format mm/dd/yyyy: " + new Date('11/30/2022 10:35:32') + "\n" + 
"format yyyy-mm-dd: " + new Date('2022-11-30 10:35:32'.replace(/-/g,'/'));

1.1.3 array

var arrayA =  [-1.2, 3.2, 15, 4.912];
arrayA[2];

1.1.4 object

var cat1 = {color:"white", age:"15", name:"GuaiGuai"};
cat1.name

1.2 Expressions

1.2.1 Numeric operations

1.2.1.1 Euler number

Math.E

1.2.1.2 pi

Math.PI

1.2.1.3 absoluate

Math.abs(-5.611)

1.2.1.4 power of e

Math.exp(2)

1.2.1.5 square root

Math.sqrt(9)

1.2.1.6 cubic root

Math.pow(27,-3)

1.2.1.7 power

Math.pow(2,5)

1.2.1.8 cosine

Math.cos(0)

1.2.1.9 sine

Math.sin(9)

1.2.1.10 tangent

Math.tan(5)

1.2.1.11 arc tangent

Math.atan(-7.3)

1.2.1.12 arc cosine

Math.acos(0.5)

1.2.1.13 arc sine

Math.asin(0.3)

1.2.1.14 natural logarithm(base-e)

Math.log(6)

1.2.1.15 common logarithm(base-10)

// ECMAScript 6 supports while ECMAScript 5.1 not support
Math.log10(6)

1.2.1.16 base-2 logarithm

// ECMAScript 6 supports while ECMAScript 5.1 not support
Math.log2(6)

1.2.1.17 round up

Math.ceil(4.13)

1.2.1.18 round down

Math.floor(4.67)

1.2.1.19 round

Math.round(4.83)

1.2.1.20 trunc

Math.trunc(4.83)

1.2.1.21 random

Math.random()

1.2.1.22 maximum

Math.max(1,2,-3)

1.2.1.23 minimum

Math.min(1,2,-3)

1.2.2 Strings operations

1.2.2.1 compare

'Hello' == 'hello' || 'a' < 'A' || 'a' != 'A'

1.2.2.2 replace first

"Hello World! World is yourself.".replace("World", "Feeling");

1.2.2.3 replace all

"Hello World! World is yourself.".replace(/World/g, "Feeling");

1.2.2.4 starts with

'Hello'.startsWith('h')

1.2.2.5 end with

'Hello'.endsWith('o')

1.2.2.6 subString

'Hello'.substring(2, 5)

1.2.2.7 char at

'hello'.charAt(2)

1.2.2.8 concat

'hello'.concat(' world')

1.2.2.9 split

'1,2,3,4'.split(',')

1.2.2.10 indexOf

'hello'.indexOf('e')

1.2.2.11 lastIndexOf

'hello'.lastIndexOf('l')

1.2.2.12 length

'hello'.length

1.2.2.13 search

var stringA = "abc1233hello";
var regexA = /3{2,}/ig;
stringA.search(regexA)

1.2.2.14 toLowerCase

'Hello'.toLowerCase()

1.2.2.15 toUpperCase

'Hello'.toUpperCase()

1.2.3 Array operations

1.2.3.1 length

var arrayA =  [-1.2, 3.2, 15, 4.912];
arrayA.length

1.2.3.2 append

var arrayA =  [-1.2, 3.2, 15, 4.912];
arrayA.push(-47);

1.2.3.3 remove

var arrayA =  [-1.2, 3.2, 15, 4.912];
arrayA.pop()

1.2.4 Boolean operations

1.2.4.1 string include

var stringA = "abc1233hello";
var regexA = /3{2,}/ig;
stringA.search(regexA) >= 0

1.2.4.2 string match

var stringA = "abc1233hello";
var regexA = /\S*3{2,}\S*/ig;
stringA.search(regexA) >= 0

1.2.4.3 array include

var arrayA =  ['A', 'B', 'C', 'D'];
arrayA.includes('C');

1.2.4.4 is number

Math.abs(2a) >= 0

1.2.4.5 and/or/not

var arrayA =  ['A', 'B', 'C', 'D'];
var stringA = "abc1233hello";
arrayA.includes('C') && (arrayA.length >= 8 || stringA.length < 5 || !stringA.endsWith("h"));

1.2.5 Date operations

1.2.5.1 date formats

"current time: " + "\n" + 
"new Date() = " + new Date()+ "\n" + 
"new Date().getTime() = " + new Date().getTime() + "\n" + 
"new Date().toLocaleString() = " + new Date().toLocaleString()+ "\n" + 
"new Date().toGMTString() = " + new Date().toGMTString()+ "\n" + 
"new Date().toISOString() = " + new Date().toISOString()+ "\n" + 
"new Date().toUTCString() = " + new Date().toUTCString()+ "\n" + 
"new Date().toString() = " + new Date().toString()+ "\n" + 
"new Date().toJSON() = " + new Date().toJSON()+ "\n" + 
"new Date().toDateString() = " + new Date().toDateString()+ "\n" + 
"new Date().toTimeString() = " + new Date().toTimeString()+ "\n" + 
"new Date().toLocaleDateString() = " + new Date().toLocaleDateString()+ "\n" + 
"new Date().toLocaleTimeString() = " + new Date().toLocaleTimeString()

1.2.5.2 parse date

new Date('2022/11/30 10:35:32').toLocaleString() + "\n" + 
new Date('11/30/2022 10:35:32').toLocaleString() + "\n" + 
new Date('2022-11-30 10:35:32'.replace(/-/g,'/')).toLocaleString() + "\n" + 
new Date('2022/11/30') + "\n" + 
new Date('2022-11-30'.replace(/-/g,'/'))

1.2.5.3 components of date

var timeb = new Date('2022/11/30 10:35:32');
"year: " + timeb.getFullYear() + "\nmonth: " + (timeb.getMonth() + 1) + "\nday: " + timeb.getDate()
 + "\nweek day: " + timeb.getDay() + "\nhours: " + timeb.getHours()+ "\nminutes: " + timeb.getMinutes()
+ "\nseconds: " + timeb.getSeconds();

1.2.5.4 compare dates

new Date('2012/05/19').getTime()  > new Date('2016/05/19 09:23:12').getTime()

1.3 Function

1.3.1 Add style

function addStyle(style) {
    var node = document.createElement("style");        
    node.id = "mystyleid";        
    node.type = "text/css";        
    node.innerHTML = style.replace(/\n/g,"  ");        
    document.getElementsByTagName("HEAD").item(0).appendChild(node);
};
addStyle("body { background-color:black; color:#CCFF99; }");

1.3.2 Remove node

function removeNode(id) {
    var node = document.getElementById(id);
    if ( node != null ) 
        node.parentNode.removeChild(node);
};
removeNode("mystyleid");

1.4 html

1.4.1 Selection

1.4.1.1 Select all

window.getSelection().removeAllRanges();     
var selection = window.getSelection();        
var range = document.createRange();        
range.selectNode(document.documentElement);        
selection.addRange(range);

1.4.1.2 Select none

window.getSelection().removeAllRanges();

1.4.1.3 Select node

function selectNode(id) {
    window.getSelection().removeAllRanges();     
    var selection = window.getSelection();        
    var range = document.createRange();        
    range.selectNode(document.getElementById(id));        
    selection.addRange(range);
};
selectNode("someid");

1.4.1.4 Current selected string

window.getSelection().toString();

1.4.1.5 Current selected html codes

var selectionObj = window.getSelection();        
var rangeObj = selectionObj.getRangeAt(0);        
var docFragment = rangeObj.cloneContents();        
var div = document.createElement("div");        
div.appendChild(docFragment);        
div.innerHTML;

1.4.2 Value

1.4.2.1 Read Cookie

document.cookie;

1.4.2.2 Page height

document.documentElement.scrollHeight || document.body.scrollHeight;

1.4.2.3 Page width

document.documentElement.scrollWidth || document.body.scrollWidth;

1.4.3 Operation

1.4.3.1 Scroll page

window.scrollTo(50,70 );

1.4.3.2 Set page as editable

document.body.contentEditable=true;

1.4.3.3 Pop information

alert("Hello");

1.4.3.4 confirm

confirm("Are you fine?");

1.4.3.5 input

prompt("Your cat");

1.4.3.6 open address

window.open("http://www.nlc.cn");

* Links and controls may be unresponsive when html page is editable.