MongoDB数据库forEach循环遍历用法

>var arr = ["ab","cd","ef"]>var show = function(value,index,ar){ print(value) }>arr.forEach(show)abcdef

//value为当前元素值，index为当前元素在数组中的索引，ar为数组本身functionShowResults(value, index, ar) {document.write("value:" + value);document.write("index: " + index);document.write("name: " + this.name);document.write("");}varletters = ['ab', 'cd', 'ef'];varscope = { name: 'scope' };// ShowResults为回调函数，scope为回调设置上下文环境，使回调函数的this指向scope变量，scope为可选参数letters.forEach(ShowResults,scope);