The factorial and 1!+2!+...+n! of JavaScript before computing

Alert (SUM (5)); function sum (num) {//initialize array var n = [];for (var i=0;i<num;i++) {n[i]=i+1;} JC (n);//Calculate the sum of the first n factorial, that is, the sum of the array return eval (n.join ("+"));} Place each factorial result into an array to form the Order multiplier Group function JC (arr) {for (Var i=1;i<arr.length;i++) {arr[i]=arr[i-1]*arr[i];} return arr;}

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The factorial and 1!+2!+...+n! of JavaScript before computing