js中如何把字符串转化为对象、数组示例代码

var test='{ colkey: "col", colsinfo: "NameList" }'

var test='{ colkey: "col", colsinfo: "NameList" }'
var obj2=eval("("+test+")");
alert(obj2.colsinfo);

var test='["colkey", "col", "colsinfo","NameList" ]'
var obj2=eval("("+test+")");
alert(obj2.length);