Demo . 1

//bad
if (age > 20) {
return true;
} else {
return false;
} //good
return age > 20;

这种一看就明白吧,没什么说的。

Demo . 2

//bad
for (var i = 0; i < arr.length; i++) {
//do something...
} //good
for (var i = 0, len = arr.length; i < len; i++) {
//do something...
}

将数组的长度进行存储,循环时就不用每次去读取一次数组长度,从而提升性能

Demo . 3

//bad
if (value !== "") {
//do something...
} //good
if (value) {
//do something...
}

js中所有 非空字符 作布尔运算时,都会返回 true,反之返回 false。 (空格 属于非空字符)

Demo . 4

//bad
if (value !== 0) {
//do something...
} //good
if (value) {
//do something...
}

js中所有 非零 数字作布尔运算时,都会返回 true, 反之返回 false。

Demo . 5

//bad
if (user.id === 10) {
if (user.name !== "") {
if (user.email === "email") {
//do something...
}
}
} //good
if(user.id === 10 && user.name !=="" && user.email === "email") {
//do something...
} //good
if (user.id !== 10) return;
if (user.name === "") return;
if (user.email !== "email") return;
//do something...

多层条件嵌套,进行 转换 或 拆分。

Demo . 6

//bad
var a = "aa";
var b = "bb";
var c = "cc";
var d; //good
var a = "aa",
b = "bb",
c = "cc",
d ;

多个变量的定义,写一个 var 即可,遵循的原则:被赋值的在前面,只是进行声明放后面(d 在最后)

Demo . 7

//bad
for (var i = 0; i < 100; i++){
str += str;
document.getElementById("box").innerHtml = str;
} //good
for (var i = 0; i < 100; i++) {
str += str;
}
document.getElementById("box").innerHtml = str;

尽可能的减少DOM操作,将DOM操作放在循环体之外,数据处理好后,只执行一次DOM操作即可。

Demo . 8

//bad
function test() {
var a = b = 1;
console.log(a);
} //good
function test() {
var a = 1,
b = 1; console.log(a);
}

避免使用 连等号 声明赋值变量。js基础好点的同学都知道,这里存在着一个坑: b 会被声明为全局变量,意思就是在 test() 方法之外b也是可以被访问到的。  全局变量是不推荐使用的,容易污染环境。

Demo . 9

//bad
if (age > 20) {
console.log("年龄大于20");
} //good
(age > 20) && console.log("年龄大于20");

这里的bad并不是说第一种写法不好,其实就可读性来说,第一种比第二种更好。 只是第二种写法更加优雅一点(个人觉得)。 这个句法可能有些同学用的比较少,解释一下:

如果第一个条件为 true ,那么就执行后面的语句,第一个条件为false, 后面的语句便不会执行。后面的语句可以是表达式,方法,或变量,常量都可以。 比如 (age > 20) && test()。用于赋值时的具体说明,如下图

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enzz17IOWg9FveNH0DDfV10VNK51LMmaZvoNX1P5yE0v/v6TqbpgMoY0OmLz/4aZ142LDfi3bJ6Xhcqc+aptfXVF8Xvcz3zWwa/2maXl+b678M//OwznQA5QaY6Y1RB7CHkyT4TNM3WEJjfV30MnXzNNMN0+tqd/3JdKB5NmR6uDycSEO+5TYpV8dMyo6ZNB43Td9gCY31ddGb7qmrOi2ZXlfb6384kQ5XLMNJsqtN0wvQlwYIw9CSTA/Vgkp3H8z0QNwknE7S+DZNr6+xvi55UdH8cJo9Fmqabtv6p1uhq3GZphvQlwaI2JLpwBboSwPEyHSMAH1pgBiZDgDjYVumLw8nbXRQD8PLez/65VtX3r3x3T8cNz7vMAzdhzevvHvjyrs3vnv7f7ssAUTLzW+UcX1a3g8A+mVbpoetnNr48a3vvPOb6M4Q7sOb1x6+bHb24ce3RHS6D292F5cf3/ruH47Dy3v7mS0yrU/b+wFA3waY6Vtec3R5ryxzax9wcx/eup3uxfUHd+9VeHEjfVTCMAzzmV5pfcr3A4DhsSTT05yeztq9BMl9eHP/44ortFENKD9q1mmoj0qFJRoerbgfAAyLDZkuX3LUWj3dXHo2i75pamXs8f67tyrdbrrBPipFma5Zn/r7AcBgWJDp2RSLLzw32q72UruOXP0Cxct7P/rlW7er7c4m+6iYMr1wfainA6M0wEzfVsV6d7wuVcfp0uHHKrNtso+KNtPL16fOfgAwEBZkeri89fqPZ+KPFq4InH94XYxJq56XEg3Pq62J+/CmdMpghaxsto+K5hipfn2K9gP9UoBRsCHTlTtifOed37RRUp9/eL3y+eN1y+jr99+7Ec28+inqjfRRESehq8stWh/TfqBfCjAOdmQ6eka/FGAkyHSE9EsBRoNMB4Dx2JlMT/qcdHwCHyeDA+jSjmR6eunN/A83K55C3gBTPxYAaMcAM32Da46ePZBy/Ph//u/vdRbTfD8WAGiJJZku5XQLp1+oPa2Oq1xr010/FgBojhWZrlw52sIpGBtkelf9WACgSTZker6YUhjq9WsvG2R6F/1YAKBpdmR625e7fHxL6itboZ7eQT8WAGiBDZnewRUvaY6rY/ayFWqnH0sY0l8FQCusyHSl4Utbh0mT+3NWO1W8zX4sYUh/FQDtsCTTdw39VQC0gkzvBf1VALSCTAeA8bAp06WTFBnEZpj6xqTHCTJN25P+NrSaAXaKPZmu3O2ocUf7x0etzbx1pr4xH98SUa7ct0i6cR33HQV2ij2ZXvks9Y3uMd1fprfYN0Y9L9Nwz7zLewzVgd1hRaarZzI2XXlxnetX7l+V/l2//WX0yMXtefRn9B9Xr8zvuGE4P7565f7BPH3C1f1VMq/1QTKTH1xzzqttWkd9YwyPug9vStdbARg5KzI9DMO2ryY1jtOjxI9Te330lzAMw3B+HGV6/IQk04/253fcZPr8WMp6s476xqTNhAVatwM7aICZ3mztxXUOkmF7Sp/p6SA9+Vdez+mib8zlvR/98i3TxbHU04GdMsBM30gzmV6t3pLqoG+MdDjUwFBnBzBGu5PpomyyPkjK5WFozPSk5r4+kOrpR/vSC6touW+M+/CmdApjmt3zD6+LsblyPkxInxlg5KzI9HaPkUbSI6Ui3L+8c+2BXEuR8lqUWeZ//PPfpIK78pIqh0nb7Buzfv+9G6Z+MvMPr2vPW6fPDDBuVmQ6ukKfGWDkyPSdQp8ZYOTIdAAYj13K9PmxrnSukxTfr+cPn1qGPjAAZLuT6V/eufagXnuA9OwXW9EHBoBqgJm+0TVHm5xd3m6m0wcGQPMsyXRxNuPkt3/6deMnUCftXJJ/4pp+qRWMJr51mX60Hz//e7/4q/QlMYI+MNH/BZwUAwybFZkunY0xm7Z1RYxunO4686R/i+Z6onymS1Mubs9FfI+iDwyZDoyBDZk+m8ohXnq6XYO1F7VlY3mmK9cciWYD9IEBYAv7Mn2T6kMV+UxfH0jhe3F7XiHTJa6TjNPpAwPAFjZkutLqZTbtrPayzhTESzNdqbGkmT6iPjCUXoCBsyLT5XrKZDptfJxuOkYqTZ+/8/OjpPyS7QMjainiAGmuwDL4PjDhbEqiAyNgSaZL2qq9oEhrP48AdMq6TF8eThgudm72s2+/zl4HRsCSTJe67TJaBIBNWZLpAIAGkOkAMB5kOgCMB5kOAONBpgPAeJDpADAeZDoAjAeZDgDjQaYDwHiQ6QAwHmQ6AIwHmT40vnvqvaoxHcAusTvTk9Ze23ZqbGo+Evk+Hts+q4bAW7h+xem+6yS0r1Fe7TiO4/CtAAyd3ZkeaSoYGwzYyh2BG+4GH3inhkjPTTelvxkjfWD4yPRN1EjqRvvB++6pF1Scbnpu8dzJdGDYqma63OD8zTfU24fuqXWN6KnT6VTXED19/nQqR6xmPtJrctPSp9eop+gy3bBcsbmT3/7p15PsRuRyWto7uUWYQr3+DUArD9KTUkriws8/oIlvXaaL+s0nZy+kLwn/3DmJpp8san5zAGhTpUxfyvewXx7+8Fvfj5JIuROy/If0nMwNpJXkn4inGOaTe5VmgrgvcynNfPTLlWY5m+Zv07E8/I9//y9l0rMH8+Te0/nVMaxg7UyvU0oP9eP0wPdFKru5Ins+06UpgbcQ8a3M2nfT7wwAfauS6csPfqpNntlUzarl4TR+nlybUOoU0oA2DTrzfJLHJ5m/9zKqhXp+PvrlqtPzkZwfecublVub/JfURurUXUzT1QF8eaaHgXd6kjz9PHl6OkjPPQSgZx1nuvLsJBnrZ/pmGblZpufXPztOV1I///TqPyQK1Bykh7pMV0bUmhcW19MDLxmn16/UA+hK1dqLlIZpJUYNSSn6DZmuPF+aqXE+mpdFEwpSMhrF6x4vruFIy1XLRfmZZQbqxU831NPrlV7qR7o209WCeGmmK7NIM11XtwFgh6rHSOV6h5RZShkkni4KEdOZ8t/ZokmmwJF/QK1oKC9RH1KSMZ/pBfPRLleZPplO878zMoNx+RDpm2+oh1RNh0hn0xrF9JrXGZmOkUrTFy/PHiXlF7nAotRSpBPcMwUW5SUcJgXsMYRzGfulrR1tfX66bvhvssEgHcCOItNLmMfZ21xHOvvZt19v9gJTAAjJdAP5dPxZ3yujot8LADO7M30I/V5m04IZ0+8FQKfszvSIfb0BMhWZghnT7wVAl8j0TWSSumjG9HsB0CH6vWjnU6/fy2w6+d3Z0VS/QvR7AdAd+r000O9FLalnV4h+LwA6Q7+X/HJr93vJp3hmBvR7AdAN+r3kl1u330vJjOn3AqAz9HvRLLdmv5fMdf6ZtaPfC4Du0O+lZLtK+71ExfT337uhXRv6vQDo0hDOZewX/V4ADAeZXoJ+LwAGhEzXot8LgEGyO9OH0O+lgWfVUK0OExXOL/yoIr551jc1HwBdsTvTI/b1Bti+nr6hqpeS+ufOyan3KgrlLYruTc0HQEfI9E3USOp++r0kpyoG3uLxNmelNDUfAB2h34t2PvX6vYTm/dNLv5foXEMvCPNX7kunM56/PHskYtow3TgfAHai30sD/V5M+6dwBdvu96J/ptLPKxl6m6YDGBz6veSXW7ffi2n/pDPoo99LXuA9+6fumabpAIaHfi/55dbt91Ke6X30e9E9l0wHxo5+L5rl1u33Yto/2idLz2q134v+2dL5iIF3Grd8MU0HMDj0eynZrtJ+L4X7p59+L4Vz0vfaNU0HMCxDOJexX/R7ATAcZHoJ+r0AGBAyXYt+LwAGye5MH16/l+XhRL0/Ri/9XsQ1RLnrhMS1Rdmm5+IBLi0ChszuTI/Y1xugsJ6unLfTT7+X6KrPwHNzdzoSUa5cZ+S74pYX6jkwAAaGTN9EYVKr52L20+8lDMMwn+lfexfSBMNp6aavDQBDQL8X7Xzq9nuRNmuWOb++l34v8fTsOL3Co5xMAwwa/V627/cip3amnl6wgu33eynKdE1PLlMJHsCA0O8lv9ya/V4qrG4//V5MmV7YpYt6OjBo9HvJL7dmv5cKmd5PvxdtpkuHQ40vo/0LMFj0e9Est2a/l+Wt1388kx7LleZ76veSy/TAW0inMKbZ7bvpfemU82EADA39Xkq2q1K/F2kJ33nnN0pJvY9+L9INLuRT0QPv9EQ3PZqTZiKAwRnCuYz9ot8LgOEg00vQ7wXAgJDpWvR7ATBIdmf68Pq9bPSsGirXYZKaOkEP7BS7Mz1iX2+A7evpG6p6KWl6SVH125UCGAEyfRM1krqXfi++J/3pXzz/vKHlA7Ad/V6089m830tufXro96L26mKkDuwQ+r1s3++lZH267/dCpgM7i34v+eXW7PdStj7d93sh04GdRb+X/HJr9nspW58e+r34rjSRejqwQ+j3olluzX4vxevTS7+XNMfVMTuAkaPfS8l2Ver3UrA+ffR7CeWWLzTkAnbJEM5l7Bf9XgAMB5legn4vAAaETNei3wuAQbI704fV70UqzmuPCjehah3GdHNRUWfP9kkXD1B/B4bM7kyP2NcbQFeRUe52JD+xh34vUbuX/L3rfFdEuXI/I+mGdtyPFBg0Mn0TuqQ2zL2Xfi+RXKar5zUa7jtq+toAMAT0e9HOp16/l+zJkiXNYeQXtdLvRUzX3GO67FFOpgEGjX4vDfR70c+9ZAVb7PciHjBnetqMV54P9XRg6Oj3kl9u3X4v+rnLM+i430vMlOmBt3hsvJM09XRg0Oj3kl9u3X4vJWvVQ7+X5DFNpkuHQ40v09bZAQwB/V40y63b70U/96Int93vJX7QzZ2vKJ3CmGa376a3uFPOhwEwNPR7KdmuKv1eio6R9tHvJW32opyKHninJ7rp0Zw0EwEMzhDOZewX/V4ADAeZXoJ+LwAGhEzXot8LgEGyO9OH1e9l42fVUKcOI2rkjlNSo0kK8HwrAENnd6ZH7OsNsH09fUM1LiWtX21npA8MH5m+iRpJ3Vu/l/q3libTgeGj34t2PvX6vRQ+v4d+L5lzGdPzzaUHNPGty3RRv/nk7IX0JeGfOyec+whYiH4vDfR7KX5+T/1edOP0wPdFKru5Ins+06Up8vVKyqw1nWMA9IZ+L/nl1u33UvL8nvq9aDNdGcCXZ7pymZLoKJAO0nMPAegZ/V7yy63b76Xk+T31e8lnujKi1rywuJ4eeMk4vX6lHkBX6PeiWW7dfi+Fz++r34su09WCeGmmK7NIM11XtwFgB/q9lGxXlX4vRc+3oN+LGJ1L0xcvzx4l5ZdsHxhRS5FOcM8UWJSXcJgUsMcQzmXsV91+L+rz6fcCoEtkeom6/V7U59PvBUCnyHStuv1eLO4PA2CXkOkAMB5kOgCMB5kOAONBpgPAeJDpADAeZDoAjAeZDgDjQaYDwHiQ6QAwHv8PjlyQ+Hb6iAQAAAAASUVORK5CYII=" alt="" />

Demo . 10

//bad
if (age > 20) {
value = "similar";
//do something...
} //good
if (age > 20 && (value = "similar")) {
//do something...
}

这个可以说是Demo9的变体,代码可读性还是第一个比较好,当你采用第二种写法时,请配合注释使用。因为有些人可能会认为你这是书写失误,少写了一个 = ,从而他自行给你补上了(value == "similar")。而你实际上是想做赋值操作的。因此你要写上注释说明,你这里不是书写失误,而是要进行赋值。

注: 根据博友留言的帮助,此处应用需小心,当你为value赋值为空串 或 0 或 null 等等(也就是说,value作布尔运算返回值为 false)的时候,整个判断表达式会返回 false, 也就不会执行if花括号里面的代码程序。所以当你不确定 value 会被赋值为什么的时候,建议不要这样用。

Demo . 11

//bad
if (value === "") {
value = "similar";
} //good
if(!value) {
value = "similar";
} //good
value = value || "similar";

这个和Demo9的 && 号运算正好相反,当第一个条件为 false 时,执行后面的语句。因为空字符串作布尔运算是返回 false的,所以可以这样用。

Demo . 12

//bad
i = i + 1;
i = i - 1; //good
i++;
i--;

这个没什么好说的。

Demo . 13

//bad
if (typeof str === "String") { } //good
if (typeof str === "string") { }

这里只是帮大家填个坑,不存在好坏。typeof 运算是用来检查数据类型的(常用来检查js中的基础类型),它返回的是一个字符串(并且始终为小写),所以第一个始终为false。 检查js中的引用类型要用 instanceof 运算, 如: var arr = [];  if(arr instanceof Array){}, 但 Function 类型比较特别,也可以用 typeof 来进行判断。

Demo . 14

//(bad) 格式化字符串 fontSize => font-size
function stringFormat(str) {
var strArr = str.split(''),
len = strArr.length,
i = 0; for (; i < len; i++) {
if(/^[A-Z]$/.test(strArr[i])) {
strArr[i] = "-" + strArr[i].toLowerCase();
}
} return strArr.join('');
} //(good) 格式化字符串 fontSize => font-size
function stringFormat(str) {
return (str.replace(/([A-Z])/g, "-$1")).toLowerCase();
}

两个方法实现同样的功能,但第二个优雅得多,性能上也比第一个要好。当对字符串进行循环操作,如:查找、替换。 首先考虑的应该是使用 正则,不应该是循环遍历。

Demo . 15

//bad
function regist(userName, userPwd, userEmail, userPhone) {
//do something...
} //good
function regist(user) {
//do something
}

当一个方法接收的参数过多的时候,可以考虑将其封装成一个json对象, 这样简单得多。

Demo . 16

var a = 1,
b = "1"; //(bad) 输出 a等于b
if (a == b) {
console.log("a等于b");
} //(good) 输出 a不等于b
if (a === b) {
console.log("a等于b");
} else {
console.log("a不等于b");
}

推荐使用 全等 判断,这样更准确。 字符串和数字并不是全等的。关于比较的一点说明:

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" alt="" />

Demo . 17

//bad
if (age > 20) {
value = "aa";
} else {
value = "bb";
} //good
value = age > 20 ? "aa" : "bb";

目前只想到这么多,麻烦大家进行补充,感谢!

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