javascript 随机抽取数组中一值

var m = [1,2,3,4,5,6,7,8,9,'a','b','c','d','e','#'];

function randArray(m, len) {
    m.sort(function () {
        return Math.random() - 0.5;
    });
    return m.slice(0, len);
}

console.log(randArray(m, 4));

var arr = [1,2,3,4,5,6,7,8,9,'php','js','shell','seo','linux','&','#'];

function getRand(arr, len) {
    //这儿用到了js的函数式写法
    arr.sort(function () {
        return Math.random()-0.5;
    });
    return arr.slice(0, len);
}
//在Chrome中的js控制台中显示
//console.log(getRand(arr, 4));
document.write('

'); 

document.writeln('随即抽取的元素为：'+getRand(arr, 3)); 

document.writeln('随即抽取的元素为：'+getRand(arr, 3).join('_'));