JS-模拟printf

```function printf(){ ???var args = [].slice.call(arguments), ???????fmt = args.shift(), ???????args_index = 0; ???///%(填充的字符)?(多一共少位)?(什么格式的)/ig ???return fmt.replace(/%(\w)?(\d)?([dfsx])/ig, function(_,char,num,form){ ???????var str = num ? char.repeat(num) : ‘‘; ???????if(form == ‘d‘) str += parseInt(args[args_index++]); ???????return num ? str.slice(num*-1) : str; ???});}String.prototype.repeat = function(num){ ???// num可能是字符串，先用num-0将num变成数字，再+1 ???return new Array(num-0+1).join(this[0] || ‘‘);}```

JS-模拟printf

原文地址：https://www.cnblogs.com/jffun-blog/p/10206590.html