Can anyone see what is wrong with my Javascript?
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18-09-2019 - |
Question
I have written the following:
var pages=["[www.google.co.uk] This is the WWW. ","[www.yahoo.co.uk] This is also the WWW. "];
function findScoresC(s){
var scores=[];
var words=[];
var wordScore;
var indexScore=[];
s=s.toLowerCase();
for(i=0;i<pages.length; i++){
var lowerCaseContents=(pages[i].substring(pages[i].indexOf("]")+1,pages[i].lastIndexOf(" "))).toLowerCase();
words=lowerCaseContents.split(" ");
for(i=0;i<words.length;i++){
if(words[i].match(s)){
wordScore=1;
indexScore[i]=indexScore[i]+1};
scores[i] =indexScore[i]}};
return scores;
}
alert(findScoresC("w"));
The function aims to return an array ("scores") where each index of the array is the number of times the string s is found in each index of the "pages" array, excluding what is inside the square brackets - however, only finding the string s once within each word. So ideally, the first index of scores would be 1, because I have called the function with the letter w, and i would only like it to find the first w of "WWW" in the first index of pages - if this makes sense.
I have confused myself pretty epically in getting this far, so I have no idea why the function is returning ",,,," rather than numerical values for each index of scores - any ideas?
Thanks
Solution
var pages=["[www.google.co.uk] This is the WWW. ","[www.yahoo.co.uk] This is also the WWW. ";
function findScoresC(s){
var scores=[];
var words=[];
s=s.toLowerCase();
for(i=0;i<pages.length; i++)
{
scores[i]=0;
var lowerCaseContents=(pages[i].substring(pages[i].indexOf("]")+1,pages[i].lastIndexOf(" "))).toLowerCase();
words=lowerCaseContents.split(" ");
for(j=0;j<words.length;j++)
{
if(words[j].match(s))
{
scores[i] += 1;
}
}
}
return scores;
}
alert(findScoresC("w"));
There were a few things. I replaced "i" with "j" for the inner index. You don't require a semicolon after a closing paren. You should have a semicolon after instructions (a couple were missing).
Probably the main issue (after the "i" issue) was that scores[i] should have been set outside the inner loop. This would have been clearer if the cosing parens had been separated out onto separate lines, instead of like "scores[i] =indexScore[i]}};
".
It turned out that the variable indexScore
was not required. That allowed me to bring scores[i]
inside the inner loop to accumulate word hits directly.
Finally, I would prefer to communicate the pages
variable to the function as an argument than to assume that it is available in the global space. I tend to avoid globals if I can.
var pages = [...];
function findScoresC(pages, s)
{
...
}
alert(findScoresC(pages, "w"));
OTHER TIPS
When your for
loop exits, i
is equal to words.length
, which is one greater than the last index of indexScore
. You are assigning nothing at all to scores[i]
each time through.
It might be because you have a nested for loop with the same index variable.
Here's you're function fixed. It returns [1,1]
which appears to be what you were going for. My notes are in the code.
var pages=["[www.google.co.uk] This is the WWW. ","[www.yahoo.co.uk] This is also the WWW. "];
function findScoresC(s){
var scores = [],
words = [],
wordScore;
// indexScore = [] <- this doesn't seem necessary
s = s.toLowerCase();
// Make sure to use `var i` and not just `i`; otherwise, you are creating a global variable.
for ( var i=0; i<pages.length; i++ ) {
// Initialize me!
scores.push(0);
var lowerCaseContents = pages[i].substring(
pages[i].indexOf("]") + 1, pages[i].lastIndexOf(" ")
).toLowerCase();
words = lowerCaseContents.split(" ");
// You were using `i` for this loop as well. No can do.
for ( var j=0; j<words.length; j++) {
if ( words[j].match(s) ) {
// wordScore = 1; <- I don't know what you're using this for
scores[i]++;
}
}
};
return scores;
}
console.log(findScoresC("w"));
here's a small function that counts how many times substring "subStr" occurs in "str", not counting [...]
function substrCount(str, subStr) {
var str = str.replace(/\[.+?\]/g, "");
var del = str.toLowerCase().split(subStr.toLowerCase()).join("");
return (str.length - del.length) / subStr.length;
}
the rest is obvious ;)
// edit: this is how you apply this function to an array
var someArray = ["whatever", "something", "else" ];
var counter = [];
for(var i = 0; i < someArray; i++)
counter[i] = substrCount(someArray[i], "something");
// or, to count only one match, i.e. just to test if a substring is present
counter[i] = substrCount(someArray[i], "something") > 0;