在ES5与ES6环境下处理函数默认参数的实现方法

function doSomething (name, age) {
 name = name || 'default name'
 age = age || 18
 console.log(name, age)
}

doSomething()    // default name, 18
doSomething('Niko') // Niko    , 18
doSomething(, 12)  // default name, 12

doSomething('Niko', 0) // Niko, 18

console.log(0     || 'wrong')
console.log(''    || 'wrong')
console.log(null   || 'wrong')
console.log(false   || 'wrong')

function doSomething (name, age) {
 if (name === undefined) {
  name = 'default name'
 }
 if (age === undefined) {
  age = 18
 }
 console.log(name, age)
}

function doSomething (name, age) {
 name = name === undefined ? 'default name' : name
 age = age === undefined ? 18       : age
 console.log(name, age)
}

function defaultValue (val, defaultVal) {
 return val === undefined ? defaultVal : val
}
function doSomething (name, age) {
 name = defaultValue(name, 'default name')
 age = defaultValue(age , 18)
 console.log(name, age)
}

function defaultValue () {
 return arguments[+(arguments[0] === undefined)]
}

function doSomething (name = 'default name', age = 18) {
 console.log(name, age)
}

function requireParams () {
 throw new Error('required params')
}
function doSomething (name = requireParams(), age = 18) {
 // do something
}

function init ({id, value}) {}
init({
 id: 'tagId',
 value: 1
})

function init ({
 id  = 'defaultId',
 value = 1
} = {}) {
 console.log(id, value)
}
init()