var a = [

  {name: "Fred", state: "MO", age: 25},

  {name: "Bobby", state: "IL", age: 34},

  {name: "Marcus", state: "MO", age: 22},

  {name: "Jenny", state: "IL", age: 39}

];

​

// Find people from MO

var ret = [];

for ( var i = 0; i < a.length; i++) {

  if ( a[i].state === "MO") {

    ret.push(a[i]);

  }

}

​

console.log(ret);

​

// 1-liner using lo-dash

console.log( _.where(a, {state: "MO"}));