JAVASCRIPT SCOPE

    // 73 - DIFFERENCES BETWEEN VAR AND LET
    let catName = "Quincy";
    var quote;

    catName = "Beau";

    function catTalk(){
        "use strict";
        catName = "Oliver";
        quote = catName + " says Meow!";
    }
    console.log("Var vs Let");
    console.log(catTalk());
    

    // 74 - SCOPES OF VAR AND LET
    // var are always accessible from anywhere
    // let can be defined in multiple places block or outside
    function checkScope(){
        "use strict";
        let i = "function scope";
        if (true){
            let i = "block scope";
            console.log("Block scope i is: ", i);
        }
        console.log("Function scope i is: ", i);
        return i;
    }
    console.log("Scope of Var and Let");
    console.log(checkScope());
    

    // 75 - CONST

    function printManyTimes(str){
        "use strict";

        const SENTENCE = str + " is cool";

        for (let i=0; i<str.length; i+=2){
            console.log(SENTENCE);
        }
    }

    console.log("Const");
    console.log(printManyTimes("Tree"));
    

    // 76 - MUTATE AN ARRAY DECLARED WITH CONST
    const s = [5, 7, 2];
    function editInPlace() {
        "use strict";

        s[0] = 2;[2,5,7];
        s[0] = 5;
        s[0] = 7;
    }
    editInPlace();
    console.log("Mutate an array declared with const");
    console.log(s);
    

    // 77 - PREVENT OBJECT MUTATION
    function freezeObj() {
        "use strict";
        const MATH_CONSTANTS = {
            PI: 3.14
        };

        Object.freeze(MATH_CONSTANTS);

        try {
            MATH_CONSTANTS.PI = 99;
        }catch( ex ) {
            console.log(ex);
        }
        return MATH_CONSTANTS.PI;
    }
    console.log("PreventObjectMutation:");
    const PI = freezeObj();