Practical, a compilation of ES6 code specification writing methods in js development

ES6 code standard writing is organized, the use of quotation marks, single quotation mark ' ' takes precedence (if it is not a nested quotation mark, do not use double quotation marks), the use of spaces: (after the keyword symbol typesetting function assignment symbol =), etc. .

1. When using quotation marks, single quotation marks ' ' take precedence (if it is not nested quotation marks, do not use double quotation marks)

Normal situation: console.log('hello there') Double quotation marks Code: $("

")

2. Issues with the use of spaces: (after the keyword symbol, after the typesetting function assignment symbol = ), etc.

　　a Function brackets: function hello (name) {} Look at (parameters) The "left and right outside the brackets" ( ) have spaces, and the "left and right name inside the brackets" have no spaces

b A space is required after the keyword: if (condition) { ... } A space is required between if and ()

c Assignment symbol = Spaces are required on both sides: var x = 2 Assignment symbol = Spaces are required on both sides

d Spaces are required on both sides of the string splicing symbol: var message = 'hello, ' name '!' The number between constants and variables, spaces are required on the left and right sides

e Comma, do not leave it in front Space, leave a space after: var list = [1, 2, 3, 4] function greet (name, options) { ... } Do not leave a space before the comma

3. Problems with the same line but different lines ：

If () {} else {}: } else { To be in one line

                                                                                                                      　　　} else {

　　　　　　　　 //

　　　　　　}

4. Do not write unused variables. If a variable is defined and has not been used in operations, it should not be defined. this variable.

5. Use === instead of ==. When comparing equal, == will take one more step of data conversion, but when in the if (a!=undefiend) {} ​​condition, a!=undefiend simultaneously There are dual meanings of a!==undefiend and a!==null (null == undefined)

6. It is customary to add window to the properties and methods of window. For some exceptions, you do not need to add window: document. console, navigator. For example: window.alert('hi')

7. The same concatenation method is very long and requires line breaks and indentation. The ternary operator in js, concatenation in jq, etc.

　var location = env.development ? 'localhost' : 'www.api.com' Written in one line

　　var location = env.development

　　　 ? 'localhost'

　　 : 'www .api.com'

var leds = stage.selectAll('.led')　　.data(data)　. enter().append('svg:svg')

　 .attr('width', (radius margin) * 2)
　 .append('svg: g')
　.attr('transform', 'translate(' (radius margin) ',' (radius margin) ')')
　 .call(tron.led);

8 , Comment question: There should be a blank line with the previous line. In addition, there should be no large blank lines for no reason.                                                                                                                                                                                                                                                                               Empty line

　　 / / Here are the comments

　 console.log(value)

: (

）

　/**

　　* based on the passed in tag name　　*　　* @param tag　　* @return element　　*/

9. Problem at the beginning: Do not start with ( [ ` , but add the ; sign
# before the beginning.
##　　;(function () {window.alert('ok')}())

　　　;[1, 2, 3].forEach(bar)　　　

10. Problems with creating objects and arrays: var item = {}; without using the new Object() method. Arrays: var arr = []

11. Problems with connecting strings of more than 80 characters:

　var errorMessage = 'This is a super long error that '

'was thrown because of Batman.'

'When you stop to think about '

'how Batman had anything to do '

'with this, you would get nowhere '

'fast.';

Use the join method for loops or multi-line strings To construct

function inbox(messages) {

items = [];

for(i = 0; i < length; i ) {

Items[i] = messages[i].message;

　}

return'

• ' items.join() ;

  }

  12. Use parseInt for numbers and always bring the base for type conversion. var val = parseInt(inputValue, 10);

  13. Use for Boolean value conversion Boolean() or!! var hasAge = Boolean(age); var hasAge = !!age;

  14. Naming problem:

  a When naming private properties, add an underscore_ in front of it, such as: In the constructor, this._firstName = 'Panda'; var _firstName = firstName;

  b Add a $ to the name of the jq variable to distinguish the js variable

  Related articles:

  Introduction and export of commonJS and es6 specifications

  Daily js development specifications

  Related videos:

  Javascript - ES6 practical video course-free online video tutorial

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