js 算出某值以内的质数

    //算出 num 以内的所有质数
 
function prime(num){
    var list = [];
    for(var i = 2; i <= num; i++){ list.push(i); } //create a Array
    
    for(var i = 0; i < list.length; i++){
        for(var j = 2; j < list[i]; j++){
            if(list[i] % j == 0){
                list.splice(i,1); //delete the non prime number.it will change the index of other elements
                j = 2; //由于splice导致list[i+1]的index变为i,因此把j置为2以便对list[i+1]进行重新计算
        }
    }
}