如何传递值而不是数组的引用?

I have this structure:

我有这个结构:

var a = [];
a.push({"level": 1, "column": 4, "parent": "none", "title": "Node 0", "content": "Parintele suprem", "show": "1"});
var b = a;

a.push({"level": 1, "column": 5, "parent": "none", "title": "Node 1", "content": "Parintele suprem", "show": "1"});

console.log(b);
var a = [];