JavaScript/Variables/Exercises

Topic: Declaration and Initialization {Which line(s) lead to an error? /* 1 */ "use strict"; /* 2 */ let a = 0; /* 3 */ a = 1; /* 4 */ const a = 10; /* 5 */ alert(a); |type="[]"} - Line 2 - Line 3 + Line 4 - Line 5 - None of the above {Which line(s) lead to an error? /* 1 */ "use strict"; /* 2 */ let a = 0; /* 3 */ a = 1; /* 4 */ const b = 10; /* 5 */ b = 100; |type="[]"} - Line 2 - Line 3 - Line 4 + Line 5 - None of the above {Which line(s) lead to an error? /* 1 */ "use strict"; /* 2 */ let a; /* 3 */ a = 1; /* 4 */ alert(a); |type="[]"} - Line 2 - Line 3 - Line 4 + None of the above {Which line(s) lead to an error? /* 1 */ "use strict"; /* 2 */ let a; /* 3 */ alert(a); /* 4 */ a = 1; /* 5 */ alert(a); |type="[]"} - Line 2 - Line 3 || The alert shows that the variable a does have a value of <code>undefined<code>. This is not considered to be an error. - Line 4 - Line 5 || The first alert shows that the variable a does have a value of <code>undefined<code>. This is not considered to be an error. + None of the above || The first alert shows that the variable a does have a value of <code>undefined<code>. This is not considered to be an error. {Which line(s) lead to an error? /* 1 */ "use strict"; /* 2 */ alert(a); /* 3 */ let a = 1; /* 4 */ alert(a); |type="[]"} + Line 2 - Line 3 - Line 4 - None of the above {Which line(s) lead to an error? /* 1 */ "use strict"; /* 2 */ { /* 3 */ const a = 1; /* 4 */ alert(a); /* 5 */ } // /* 6 */ alert(a); |type="[]"} - Line 2 - Line 3 - Line 4 - Line 5 + Line 6 - None of the above Be creative Explain to your colleague why programs need variables. Create a code snippet that defines a variable within a block scope. Access this variable within the block scope and outside of the block scope. Discuss with your colleague the advantages and disadvantages of using the global context.