str is a string. Return a string containing only the seventh character of the string UNLESS the string is shorter than seven characters, in which case return null.

javascript programming
exercise: strings 01

<html>
<script>

function seventhChar(str) {
  var value;
  // ADD CODE UNDER THIS LINE
  
  return value;
}

var testAA = [
  ["Hey, there guys!", "h"],
  ["abracadabra", "d"],
  ["What?", null]
];

function cloneTree(obj) {
  if (obj === null)
    return null;
  if (typeof obj !== "object")
    return obj;
  var newobj = {};
  for (var prop in obj) {
    newobj[prop] = cloneTree(obj[prop]);
  }
  return newobj;
}

var argAAS = [];
for (var i=0;i<testAA.length;i++) {
  argAAS.push( [] );
  for (var j=0;j<testAA[i].length-1;j++) {
    argAAS[i].push( str(testAA[i][j]) );
  }
}

var testFunction = seventhChar;

function runTests(func,testAA) {
  var answerA = [];
  for (var i=0;i<testAA.length;++i)
    answerA.push( func.apply(null,testAA[i]) );
  return answerA;
}

function str(x) {
  return JSON.stringify(x);
}

function run() {
  var error = null;
  var answerA;
  try {
    answerA = runTests(testFunction, testAA);
  }
  catch (err) {
    error = err;
  }
  if (error!==null)
    document.write("<b>Runtime error!</b>  ("+error+")<br>");
  document.write("<table>");
  document.write("<tr>");
  document.write("<th>Result</th>");
  document.write("<th>Your Value</th>");
  document.write("<th>Correct Value</th>");
  document.write("<th>str</th>");
  document.write("</tr>");
  var nArgs = testAA[0].length-1;
  for (var i=0;i<testAA.length;++i) {
    document.write("<tr>");
    if ( str(testAA[i][nArgs])==str(answerA[i]) )
      document.write("<td>pass</td>");
    else
      document.write("<td>FAIL</td>");
    document.write("<td><pre>"+str(answerA[i])+"</pre></td>");
    document.write("<td><pre>"+str(testAA[i][nArgs])+"</pre></td>");
    for (var j=0;j<nArgs;j++)
      document.write("<td>"+argAAS[i][j]+"</td>");
    document.write("</tr>");
  }
  document.write("</table>");
}

run();
</script>

<style>
table { border-spacing: 15px 5px; }
th { text-align:center; }
td { text-align:center; }
</style>
</html>