current position:Home>JS practical review notes (6)
JS practical review notes (6)
2021-08-26 00:37:10 【XiLan】
1、 Browser debugging
F12
As we can see , There are three main ways to pause a script :
- A breakpoint . ( Call directly on the console )
- The
debugger
Statement .( Write... In the code debugger ) - error ( If the development tool is open and the button yes “ open ”).
2、 Write code Partial specification
1、 Of course, you can configure it directly first vscode prettier When saving Just format the code
-
Beginners sometimes do this .this is wrong , You don't need curly braces :
if (n < 0) { alert(`Power ${n} is not supported`); } Copy code
-
Split into separate lines , Without curly braces . Never do this , Error prone when adding new rows :
if (n < 0) alert(`do somethings`); Copy code
-
A line without braces - Acceptable , If it's short :
if (n < 0) alert(`do somethings`); Copy code
2、 A long part Show it in multiple lines
As shown below :
test(data1,
data2,
data3,
data4,
another
) {
// ...
}
Copy code
3、 Boundary Write first The boundary conditions
- this is wrong
for (let i = 0; i < 6; i++) {
if (code) {
... //
}
}
Copy code
- this is right
for (let i = 0; i < 6; i++) {
if (!code) continue;
... //
}
Copy code
- More styles details - Airbnb JavaScript Style guide
4、 Code checking Use eslint
Need configuration .eslintrc
- Write simple Easy to read accord with Standard code It's just Pursuit
3、 Write notes
1、 Good code should Basically no comments are needed Follow the method You might know what you're doing
2、 The functions in a function Disassemble into multiple function
Sometimes it's useful to replace code snippets with functions , As shown below :( Not split )
function test(n) {
nextP:
for (let i = 2; i < n; i++) {
for (let j = 2; j < n; j++) {
if (i % j == 0) continue nextP;
}
alert(i);
}
}
Copy code
- this is right
A better variant , With decomposition function isPrime
:
function test(n) {
for (let i = 2; i < n; i++) {
if (!nextP(i)) continue;
alert(i);
}
}
function nextP(n) {
for (let i = 2; i < n; i++) {
if (n % i == 0) return false;
}
return true;
}
Copy code
3、 Good annotation structure
-
Record function parameters and usage
There is a special grammar JSDoc To record functions : usage 、 Parameters 、 Return value .
for example :
/**
* Returns x raised to the n-th power.
*
* @param {number} x The number to raise.
* @param {number} n The power, must be a natural number.
* @return {number} x raised to the n-th power.
*/
function pow(x, n) {
...
}
Copy code
4、 Other specifications
1、 name Don't abbreviate
list
→lst
.userAgent
→ua
.browser
→brsr
.
2、 When selecting a name , Try to use the most abstract words . image obj
,data
,value
,item
,elem
etc.
3、 Name the function As far as possible Named after the action of this function It starts with lowercase
4、 Don't Use at will Underline naming It can lead to Confused I wonder if this is Special usage lodash With the exception of ( There is a library _ )
5、 The code needs to be tested , There is an automated test library , Let's talk about it later
copyright notice
author[XiLan],Please bring the original link to reprint, thank you.
https://en.qdmana.com/2021/08/20210826003707310z.html
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