Javascript比较两个数组并获取不匹配的值

Question

I really appreciate all your help on this.

I have two arrays:

• the first array contains file names without an extension
• the second array contains file names that have an extension .

I need to output a third array, in this case FinalArray that contains a list of all the ArrayFileNameWExt that are not in the ArrayFileName array.

I know I had a thread on finding matched items, which was great. But I'm having problems finding the unmatched items. I changed the == comparison to !== and that gave me one file name a hundred times.

Thank you for your help on this, Maxine

var ArrayFileName = ['one', 'two', 'three', 'three', 'five', 'six', 'ten'];
var ArrayFileNameWExt = ['one.txt', 'two.txt', 'three.txt', 'ten.wmf', 'eleven.cgm'];
var FinalArray = [];

for (var i = 0; i < ArrayFileName.length; i++) {
    for (var j = 0; j < ArrayFileNameWExt.length; j++) {
        var temp = ArrayFileNameWExt[j].split(".");
        if(ArrayFileName[i]!==temp[0]){
            FinalArray.push(ArrayFileNameWExt[j]);
            break;
        }
    }
}

Answer 1

You could use a simple filter and return all the items for which the first part of the split is not in the ArrayFileName array.

 var ArrayFileName = ['one', 'two', 'three', 'three', 'five', 'six', 'ten']; var ArrayFileNameWExt = ['one.txt', 'two.txt', 'three.txt', 'ten.wmf', 'eleven.cgm']; var final = ArrayFileNameWExt.filter(function(item) { return !ArrayFileName.includes(item.split('.')[0]); }) console.log(final); 

If you're using a pretty old version of javascript, the includes Array method might not exist. The following code could be used instead.

 var ArrayFileName = ['one', 'two', 'three', 'three', 'five', 'six', 'ten']; var ArrayFileNameWExt = ['one.txt', 'two.txt', 'three.txt', 'ten.wmf', 'eleven.cgm']; var final = ArrayFileNameWExt.filter(function(item) { var name = item.split('.')[0]; for (var i = 0; i < ArrayFileName.length; i++) { if (ArrayFileName[i] === name) return false; } return true; }) console.log(final); 

Answer 2

Reusing the code you gave us, I made this: I interchanged the two for-loops and I used a variable ( found ) to keep track of the found items. Iterating through ArrayFileNameWExt in the outer loop is also better because we lower the number of calls to the split function.

 var ArrayFileName = ['one', 'two', 'three', 'three', 'five', 'six', 'ten']; var ArrayFileNameWExt = ['one.txt', 'two.txt', 'three.txt', 'ten.wmf', 'eleven.cgm']; var FinalArray = []; for (var i = 0; i < ArrayFileNameWExt.length; ++i) { var temp = ArrayFileNameWExt[i].split("."); var found = false; for (var j = 0; j < ArrayFileName.length; ++j) { if (ArrayFileName[j] === temp[0]) { found = true; break; } } if (!found) { FinalArray.push(ArrayFileNameWExt[i]); } } console.log(FinalArray); 

Cheers!

Answer 3

I would use .filter and .includes -

 const fileNames = ['one', 'two', 'three', 'three', 'five', 'six', 'ten'] const fileNamesWExt = [ 'one.txt', 'two.txt', 'three.txt', 'ten.wmf', 'eleven.cgm' ] const basename = filename => filename.split(/\\.[^.]+$/)[0] const finalArray = fileNamesWExt.filter(f => ! fileNames.includes(basename(f))) console.log(finalArray) // [ 'eleven.cgm' ] 

Note our implementation of basename , which is careful to only remove the last extension -

 const basename = filename => filename.split(/\\.[^.]+$/)[0] console.log ( basename ("cat") // "cat" , basename ("cat.dog") // "cat" , basename ("cat.dog.eel") // "cat.dog" , basename ("cat.dog.eel.fox") // "cat.dog.eel" ) 

If you cannot use arrow functions, you are probably using a pretty old version of JavaScript. In this case, you'll also need to polyfill .includes -

 Array.prototype.includes = function (x, init) { for (var i = init || 0; i < this.length; i = i + 1) if (this[i] === x) return true; return false; }; var fileNames = ['one', 'two', 'three', 'three', 'five', 'six', 'ten']; var fileNamesWExt = [ 'one.txt', 'two.txt', 'three.txt', 'ten.wmf', 'eleven.cgm' ]; var basename = function (filename) { return filename.split(/\\.[^.]+$/)[0]; }; var finalArray = fileNamesWExt.filter(function (f) { return ! fileNames.includes(basename(f)); }); console.log(finalArray); // [ 'eleven.cgm' ] 

Answer 4

Perhaps Editor would like this

 var ArrayFileName = ['one', 'two', 'three', 'three', 'five', 'six', 'ten']; var ArrayFileNameWExt = ['one.txt', 'two.txt', 'three.txt', 'ten.wmf', 'eleven.cgm']; var FinalArray = []; for (var i = 0; i < ArrayFileNameWExt.length; i++) { var matchFound = false; for (var j = 0; j < ArrayFileName.length; j++) { var temp = ArrayFileNameWExt[i].split("."); if(ArrayFileName[j]==temp[0]){ matchFound = true; break; } } if(!matchFound){ FinalArray.push(ArrayFileNameWExt[i]) } } console.log(FinalArray) 

Answer 5

Array#filter lets you include (or delete) the elements that meet certain condition.

Array#inludes returns if certain element is included in the array.

String#split returns an array with the elements from splitting the string using the separator that you want (in this case, the point).

 var ArrayFileName = ['one', 'two', 'three', 'three', 'five', 'six', 'ten']; var ArrayFileNameWExt = ['one.txt', 'two.txt', 'three.txt', 'ten.wmf', 'eleven.cgm']; var FinalArray = []; FinalArray = ArrayFileNameWExt.filter (filenameWExt => !ArrayFileName.includes(filenameWExt.split('.')[0])); console.log(FinalArray); 

Any further question let me know in the comments and I'll explain