js手写——函数柯里化

// 库里化：将多参数函数转成单参数函数链 -> fn(a,b,c) -> fn(a)(b)(c)// 如何知道参数收集完：比较fn.length(形参个数)和已经收集的个数，够了就执行，不够就返回新函数继续收集// 根据fn.length进行定长判断的版本constcurry=(fn)=>{returnfunctioncurried(...args){if(args.length>=fn.length){returnfn.apply(this,args);}else{return(...rest)=>curried(...args,...rest);}}}/* // 测试 const add = (a,b,c) => a+b+c; const curryAdd = curry(add); console.log(curryAdd(1)(2)(3)); console.log(curryAdd(1,2)(3)); console.log(curryAdd(1,2,3)); console.log(curryAdd(1,2,3,4)); */// 占位符版本const_=Symbol('placeHolder');constcurry2=(fn)=>{returnfunctioncurried(...args){// 检查已有的非占位参数是否已经够了constcompleted=args.length>=fn.length&&args.slice(0,fn.length).every(arg=>arg!==_);if(completed)returnfn.apply(this,args);// 参数不够，返回一个接受新参数的函数return(...next)=>{// 遍历老参数，遇到_就用新参数填坑，剩下的追加到后面constcombineArgs=args.map(arg=>(arg===_&&next.length>0)?next.shift():arg).concat(next);returncurried(...combineArgs);}}}// 测试constlogABC=(a,b,c)=>console.log(a,b,c);constcurried=curry2(logABC);curried(_,2)(1,3);curried(1)(_,3)(2);curried(_,_,3)(1)(2)