js小的代码段

判断元素是否在列表数组中

• 概述

    array.includes(item, fromIndex)
    string.includes(substring, fromIndex)
  

• 详解

数组列表

举例：

const array = [1, 2, 3];
const value = 1;
const isInArray = array.includes(value);
console.log(isInArray); // true

特殊情况

此处传入的obj1，其实是个object

但是数值对比：

console.log("typeof obj1=" +  (typeof obj1))
// typeof obj1=object
if(obj1 == 1903654775) {

也是返回true的

所以之前误以为用：

let ApkUtilReadJsonKeyList = [-262969152, 1903654773, 1114793335, 1896449818, 1903654775 ]

if(ApkUtilReadJsonKeyList.includes(obj1)) {

是可行的。结果实际不行。

实际要改为：

把obj1的object，转换成Number：

let ApkUtilReadJsonKeyList = [-262969152, 1903654773, 1114793335, 1896449818, 1903654775 ]
var objInt = Number(obj1)

// if(obj1 == 1903654775) {
// if(obj1 in ApkUtilReadJsonKeyList) {
// if(ApkUtilReadJsonKeyList.includes(obj1)) {
if(ApkUtilReadJsonKeyList.includes(objInt)) {
    // 1903654775 == 0x71777777
    isPrintStack = true
    console.log("typeof obj1=" +  (typeof obj1))
    console.log("typeof objInt=" +  (typeof objInt))
    console.log("objInt=" + objInt)
    console.log("found HashMap.put for ApkUtilReadJsonKeyList")

才可以

typeof obj1=object
typeof objInt=number
objInt=1903654775
found HashMap.put for ApkUtilReadJsonKeyList

字符串

判断主字符串是否包含子字符串：

• 概述：用str的includes

    mainString.includes(subString)
  

• 详解

测试代码：

  var mainStr = "Stack: X.0Pru.LIZ(Native Method)"
  var subStr = "X.0Pru.LIZ"
  var isMatch = mainStr.includes(subStr)
  console.log("isMatch=" + isMatch)

输出：

isMatch=true

判断字符串是否在dict的key中

• 判断key是否在字典dict中

    curKey in someDict
  

举例：

let cfgPrintOnceStackExceptionDict = {
    // key: arg list(arg0, arg1, ...)
    "+[NSURLRequest requestWithURL:]": [],
    "+[WAURLQueryItem queryItemWithName:value:]": ["ENC", undefined],
}

var iOSObjCallStr = "+[WAURLQueryItem queryItemWithName:value:]"
var isMatch = iOSObjCallStr in cfgPrintOnceStackExceptionDict
console.log("isMatch=" + isMatch)

输出：isMatch=true

获取列表的子列表

var argList = [0, 1, 2, 3, 4]
var subArgList = argList.slice(2)
console.log("argList=" + argList + " -> subArgList=" + subArgList)

输出：

argList=0,1,2,3,4 -> subArgList=2,3,4

函数默认参数

定义=写法 举例：

function printFunctionCallAndStack(funcName, funcParaDict, ThrowableCls, filterList=undefined){
...
  if (filterList != undefined) {
    ...
  }
...
}

调用：

• 不传递（带默认参数值的）最后一个参数

    printFunctionCallAndStack(funcName, funcParaDict, ThrowableCls)
  

• 传递（带默认参数值的）最后一个参数

    printFunctionCallAndStack(funcName, funcParaDict, ThrowableCls, ["X.0Pru.LIZ"])