Seven details that JavaScript beginners should pay attention to
Every language has its special features. For JavaScript, you can use var to declare variables of any type. This scripting language seems very simple, but writing elegant code requires continuous accumulation of experience. . This article lists seven details that JavaScript beginners should pay attention to and share them with you.
(1) Simplify the code
It is very simple to define objects and arrays in JavaScript. We want to create an object, which is usually written like this:
1 var
car =
new
Object();
2 car. color =
red
;
3 car.wheels = 4;
4 car.hubcaps =
spinning
;
5 car.age = 4;
The following writing can achieve the same effect:
1 var
car = {
2
colour:
red
,
3
wheels:4,
4 hubcaps:
spinning
,
5 age:4
6 }
The following writing is much shorter, and you don’t need to repeat it. Object name. Be careful not to add a semicolon after the braces, otherwise an error will occur in IE.
In addition, there is also a concise way to write arrays. In the past, we declared arrays like this:
1 var
moviesThatNeedBetterWriters =
new
Array(
2
Transformers
,
Transformers2
,
Avatar
,
Indiana Jones 4
3 );
A more concise way of writing it is:
1 var
moviesThatNeedBetterWriters = [
2
Transformers
,
Transformers2
,
Avatar
,
Indiana Jones 4
3 ];
For arrays, There is also such a special thing as associative array. You will find that a lot of code defines objects like this:
1 var
car =
new
Array();
2 car[
colour
] =
red
;
3 car[
wheels
] = 4 ;
4 car[
hubcaps
] =
spinning
;
5 car[
age
] = 4;
This is crazy, don’t get confused, “associative array” is just an alias for an object. Another way to simplify the code is to use the ternary operator, for example:
1 var
direction;
2 if
(x < 200){
3
direction = 1;
4 }
else
{
5
direction = -1;
6 }
We can use the following code to replace this writing:
1 var
direction = x < 200 ? 1 : -1;
(2) Using JSON As a data format, the great Douglas Crockford invented the JSON data format to store data. You can use native javascript methods to store complex data without any additional conversion, for example:
01 var
band = {
02
"name"
:
"The Red Hot Chili Peppers"
,
03
"members"
:[
04
{
05
"name"
:
"Anthony Kiedis"
,
06
"role"
:
"lead vocals"
07
},
08
{
09
"name"
:
"Michael Flea Balzary"
,
10
"role"
:
"bass guitar, trumpet, backing vocals"
11
},
12
{
13
"name"
:
"Chad Smith"
,
14
"role"
:
"drums,percussion"
15
},
16
{
17
"name"
:
"John Frusciante"
,
18 "role"
:
"Lead Guitar"
19
}
20
],
21
"year"
:
"2009"
22 }
01 < >Native function >
div
id
=
"delicious"
>
div
><
script
>
02 function delicious(o){
03
var out = <
ul
>; i].u + "
> +
06
o[i].d +
a
>
li
>;
07
}
08
out +=
ul
>;
09
document.getElementById(delicious).innerHTML = out;
10 }
11
script
> "http:// feeds.delicious.com/v2/json/codepo8/javascript?count=15&callback=delicious"
>
script
>
Here we call delicious's web service to get the latest bookmarks, return them in JSON format, and then They are displayed as an unordered list. Essentially, JSON is the most lightweight way for describing complex data, and it runs directly in the browser. You can even use it by calling the json_decode() function in PHP.
1 "FONT-FAMILY: 宋体; mso-ascii-font-family: Times New Roman; mso-hansi-font-family: Times New Roman"
>"FONT-SIZE: 14pt"
>(3)"FONT-SIZE: 14pt"
>"FONT-FAMILY: 宋体; mso-ascii-font-family: Times New Roman; mso-hansi-font-family: Times New Roman"
>Use < SPAN>"FONT-FAMILY: Times New Roman"
face=
"Times New Roman"
>Javascript"FONT-FAMILY : Times New Roman; mso-ascii-font-family: Times New Roman; mso-hansi-font-family: Times New Roman"
To find the maximum number in a set of numbers, we might write a loop, for example:
1 var
numbers = [3,342,23,22,124];
2 var
max = 0;
3 for
(
var
i=0;i
(numbers[i] > max){
5max = numbers[i];
6}
7 }
8 alert(max);
In fact, the same function can be achieved without looping:
1 var
numbers = [3,342,23,22,124];
2 numbers.sort(
function
(a, b){
return
b - a});
3 alert(numbers[0]);
And the simplest way to write it is:
1 Math.max(12,123,3,2,433,4);
1 var
scrollTop= Math.max(
2
doc.documentElement.scrollTop,
3
doc.body.scrollTop
4);
addclass(elm,newclass){
var
c = elm.className;
3
elm.className = (c ===
) ? newclass : c+
+newclass;
addclass(elm,newclass){
2
var
classes = elm.className.split(
);
3
classes.push(newclass);
4
elm.className = classes.join(
5 }
(4) Event delegation
Events are a very important part of JavaScript. We want to bind click events to links in a list. The general approach is to write a loop and bind events to each link object. The HTML code is as follows:
1
Great Web resources
2
- "resources"
- "http://opera.com/wsc"
>Opera Web Standards Curriculum
>
3

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