diff --git a/challenges/02-javascript-algorithms-and-data-structures/es6.json b/challenges/02-javascript-algorithms-and-data-structures/es6.json index b3370ed019..695eb91080 100644 --- a/challenges/02-javascript-algorithms-and-data-structures/es6.json +++ b/challenges/02-javascript-algorithms-and-data-structures/es6.json @@ -75,33 +75,33 @@ "
var numArray = [];
for (var i = 0; i < 3; i++) {
numArray.push(i);
}
console.log(numArray);
// returns [0, 1, 2]
console.log(i);
// returns 3
", "With the var keyword, i is declared globally. So when i++ is executed, it updates the global variable. This code is similiar to the following:", "
var numArray = [];
var i;
for (i = 0; i < 3; i++) {
numArray.push(i);
}
console.log(numArray);
// returns [0, 1, 2]
console.log(i);
// returns 3
", - "This behavior will cause problems when you create a function and store it for later use inside the for loop that uses the i variable. This is because the stored function will always refer to the value of the updated global i variable.", + "This behavior will cause problems if you were to create a function and store it for later use inside a for loop that uses the i variable. This is because the stored function will always refer to the value of the updated global i variable.", "
var printNumTwo;
for (var i = 0; i < 3; i++) {
if(i === 2){
printNumTwo = function() {
return i;
};
}
}
console.log(printNumTwo());
// returns 3
", "As you can see, printNumTwo() prints 3 and not 2. This is because the value assigned to i was updated and the printNumTwo() returns the global i and not the value i had when the function was created in the for loop. The let keyword does not follow this behavior:", "
'use strict';
let printNumTwo;
for (let i = 0; i < 3; i++) {
if (i === 2) {
printNumTwo = function() {
return i;
};
}
}
console.log(printNumTwo());
// returns 2
console.log(i);
// returns \"i is not defined\"
", "i is not defined because it was not declared in the global scope. It is only declared within the for loop statement. printNumTwo() returned the correct value because three different i variables with unique values (0, 1, and 2) were created by the let keyword within the loop statement.", "
", - "Fix the code so that each camper returns their correct index when they are called.", - "Note
Remember to add \"use strict\"; to the top of your code." + "Fix the code so that i declared in the if statement is a separate variable than i declared in the first line of the function. Be certain not to use the var keyword anywhere in your code.", + "Note
Remember to add \"use strict\"; to the top of your code.", + "This exercise is designed to illustrate the difference between how var and let keywords assign scope to the declared variable. When programming a function similar to the one used in this exercise, it is often better to use different variable names to avoid confusion." ], "challengeSeed": [ - "var newCampers = [{camper: \"Wil\"}, {camper: \"Sam\"}, {camper: \"Dav\"}];", - "// only change code below this line", - "for (var i = 0; i < newCampers.length; i++) {", - "// only change code above this line", - " newCampers[i].roleCall = function() {", - " return \"Camper # \" + (i + 1) + \" has arrived.\";", - " };", + "function checkScope() {", + " var i = \"function scope\";", + " if (true) {", + " i = \"block scope\";", + " console.log(\"Block scope i is: \", i);", + " }", + " console.log(\"Function scope i is: \", i);", + " return i;", "}", - "// test your code", - "console.log(newCampers[0].roleCall());", - "console.log(newCampers[1].roleCall());", - "console.log(newCampers[2].roleCall());" + "// only change the code above this line", + "checkScope();" ], "tests": [ - "assert(newCampers[0].roleCall() === \"Camper # 1 has arrived.\", 'message: newCampers[0].call() should call the index of the first camper');", - "assert(newCampers[1].roleCall() === \"Camper # 2 has arrived.\", 'message: newCampers[1].call() should call the index of the second camper');", - "assert(newCampers[2].roleCall() === \"Camper # 3 has arrived.\", 'message: newCampers[2].call() should call the index of the third camper');" + "// TEMPORARILY COMMENTED OUT: assert(!/var/g.test(code) && /let/g.test(code), 'message: The var keyword should be replaced with let. (This test is temporarily disabled)');", + "assert(code.match(/(i\\s*=\\s*).*\\s*.*\\s*.*\\1('|\")block\\s*scope\\2/g), 'message: The variable i declared in the if statement should equal \"block scope\".');", + "assert(checkScope() === \"function scope\", 'message: checkScope() should return \"function scope\"');" ], "type": "waypoint", "challengeType": 1,