21.1. Programming for the web
A subsection of Information Technology, 9626, through 21. Programming for the web
Listing 10 of 46 questions
JavaScript can be embedded in the code of web pages to add interactivity to a page. Jonas uses JavaScript code to store, list and display the names of cities on a web page. Two methods of storing the names are shown below. Method 1: var city1 = "London"; var city2 = "Cambridge"; var city3 = "Oxford"; var city4 = "Manchester"; Method 2: var city = ["London", "Cambridge", "Oxford", "Manchester"]; Explain why storing the names using Method 2 is more suitable for storing large numbers of cities. Jonas has added some lines to the JavaScript code: /* The code below stores the list of cities. */ var city = ["London", "Cambridge", "Oxford", "Manchester"]; Explain why Jonas would have added the new code to the script. Jonas wants to extract ‘Oxford’ from the list in the code below to display it on the web page. var city = ["London", "Cambridge", "Oxford", "Manchester"]; Write a line of JavaScript code to access the list and store the city name. Write a loop in JavaScript code to extract and display the first three city names.
9626_m17_qp_32
THEORY
2017
Paper 3, Variant 2
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Errors in JavaScript code can cause the code to fail to execute when run by a web browser. The code shown is intended to display a table on a web page when run in a web browser. The line numbers are shown only for your convenience when referencing the code in your answers. tableout = "" for (b = 1; b ": for (g = 1; g " + b * g + ""; } 10 tableout = tableout + ""; 11 } 12 tableout = tableout + ""; 13 document.write ; The code does not run as intended in web browsers because there is an error in the code. Describe how the error in the code prevents the web browser from running as intended. Errors can be ‘trapped’ in order that the performance of the web browser is not affected. Explain how you can use error handling techniques to trap errors in JavaScript code.
9626_m19_qp_32
THEORY
2019
Paper 3, Variant 2
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In JavaScript, conditional statements can be used to carry out specific actions based upon different conditions. The value of the variable ‘age’ is entered into a web page and collected by the HTML code of the page. The function in uses the ‘if else’ and ‘else if’ conditional statements to test the value of the variable ‘age’. Line numbers are shown only for your convenience when referring to the code. function myFunction() { var statement; var age = document.getElementById("age").value; if (age The code could have been written using the ‘switch’ function, e.g. lines 4 to 7 could have been: switch{ case age
9626_m20_qp_32
THEORY
2020
Paper 3, Variant 2
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Frank is a web designer who writes his own code and uses JavaScript on his webpages. He wants to print his name on every page. He creates two versions of the code to run his JavaScript on the webpage. These versions are represented here: Version 1: document.write ("My name is Frank "); Version 2: where the instructions for writing Frank’s name are in the file called “FranksJavaScriptcode.js” Explain why Frank prefers to use Version 2 of the code.
9626_s17_qp_31
THEORY
2017
Paper 3, Variant 1
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Frank is a web designer who writes his own code and uses JavaScript on his webpages. He wants to print his name on every page. He creates two versions of the code to run his JavaScript on the webpage. These versions are represented here: Version 1: document.write ("My name is Frank "); Version 2: where the instructions for writing Frank’s name are in the file called “FranksJavaScriptcode.js” Explain why Frank prefers to use Version 2 of the code.
9626_s17_qp_33
THEORY
2017
Paper 3, Variant 3
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Questions Discovered
46