有一个JS数组，如：
var arr = [["projectname1","projectnumber1"],["projectname2","projectnumber2"],["projectname3","projectnumber3"]];
想将此数组转换成JSON字符串，如：
var jsonarr = [{"projectname":projectname1,"projectnumber":projectnumber1},{"projectname":projectname2,"projectnumber":projectnumber2},{"projectname":projectname3,"projectnumber":projectnumber3}];
方法如下：
function tojson(arr){ if(!arr.length) return null; var i = 0; len = arr.length, array = []; for(;i<len;i++){ array.push({"projectname":arr[i][0],"projectnumber":arr[i][1]}); } return JSON.stringify(array); }