Little notes about JavaScript syntax

1. The pop() function is used to move the last element in the group; the shift() function moves the first item in the array, and unshift (moves in) an element to the head of the arrays.

For example:

varMyArray = [["John", at], ["Dog",3]];varA=myarray.pop ();//var myArray = [["John", 23]]; Move out the lastvarA=myarray.shift ();//var myArray = [["Dog", 3]]; move out of the firstvarC=myarray.unshift (["CCC",1]);//var myArray =[["CCC", 1],["John", [["Dog", 3]]; Array ["CCC", 1] inserted the head, became the first

2, all the comparison operators return a Boolean value, or it is either true false . Use if/else statements to do comparisons and then return true or false have become a consensus among everyone:

For example:

function IsEqual (b) {  if (a = = b)    {returntrue;   Else  {    returnfalse;}  }

can be simplified into:

function IsEqual (b) {  return a = = = b;}

3, there are two ways to access the object properties, one is the dot operator ( . ), one is the bracket operator ( [] ). When you know the name of the property, use the dot operator.

1) dot operator ( . )

For example:

varMYOBJ ={ Prop1:"Val1", prop2:"Val2"};varProp1val = MYOBJ.PROP1;//Val1varProp2val = MYOBJ.PROP2;//Val2//orvarTestobj = {   "Hat": "Ballcap", "shirt": "Jersey","Shoes":"Cleats"};varHatvalue = Testobj.hat;//BallcapvarShirtvalue = Testobj.shirt;//jersey

2) Bracket operator ( [] ): If the name of the property you want to access has a space, you can only use the bracket operator ( [] ).

varMYOBJ = {  "Space Name":"Kirk",  "More Space":"Spock"};myobj["Space Name"];//Kirkmyobj['More Space'];//Spock

Tip: If there are spaces in the attribute name, you must enclose the attribute name in single or double quotation marks.

Little notes about JavaScript syntax