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I have been trying to loop through an unordered list of numbers with javascript. The function should store all of the numbers in an array so I can find which numbers are duplicates. Any help would be appreciated. So far I have:
<html>
<head>
<title></title>
</head>
<body>
<ul id="ul">
<li>6</li>
<li>3</li>
<li>1</li>
<li>4</li>
<li>7</li>
<li>4</li>
<li>2</li>
<li>8</li>
<li>9</li>
<li>2</li>
</ul>
</body>
</html>
and a start on the javascript:
(function(){
var nums = document.getElementById("ul");
var listItem = nums.getElementsByTagName("li");
var newNums = "";
var dups = function(){
for (var i = 0; i < listItem.length; i++){
}
}; dups();
})();
what am I missing?
906
If we want to loop through an array, we can use the length property to specify that the loop should continue until we reach the last element of our array. In the loop above, we first initialized the index number so that it begins with 0 .
JavaScript does not offer any specific in-built function to traverse the array elements/objects. You can traverse an array simply using for loop or directly by element index. An array contains multiple elements of the same type, which can be traverse using for loop.
var nums = document.getElementById("ul");
var listItem = nums.getElementsByTagName("li");
var newNums = [];
for (var i=0; i < listItem.length; i++) {
newNums.push( parseInt( listItem[i].innerHTML, 10 ) );
}
FIDDLE
To not get duplicated values you can do
for (var i=0; i < listItem.length; i++) {
var num = parseInt( listItem[i].innerHTML, 10 );
if (newNums.indexOf(num) === -1) {
newNums.push( num );
}
}
FIDDLE
And to also get an array with the values that appear more than once
var newNums = [],
duplicate = [];
for (var i=0; i < listItem.length; i++) {
var num = parseInt( listItem[i].innerHTML, 10 );
if (newNums.indexOf(num) === -1) {
newNums.push( num );
}else{
duplicate.push( num );
}
}
FIDDLE
Array.indexOf might not be supported in all browsers, but there's a polyfill over at MDN
89
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