Tips for retrieving input values when they are not available in HTML documents

Question

Tips for retrieving input values when they are not available in HTML documents

In this code snippet, I am creating an input element with the file type without adding it to the DOM. My goal is to retrieve the value of this input once the user selects a file. Even though the input is not part of the HTML template, I still want to access its value.

                    <p-splitButton
                        label="Add document"
                        icon="pi pi-plus"
                        (onClick)="openAddDocument()"
                        [model]="addDocumentButtonMenuItems"
                        styleClass="p-button-help"
                    ></p-splitButton>

public readonly addDocumentButtonMenuItems = [
    {
        label: 'Download document', icon: 'pi pi-upload', command: () => {
            this.uploadFile();
        },
    },
];

public uploadFile(): void {
        const input = document.createElement('input');
        input.type = 'file';
        input.click();
    }

Is there a way to get the value from this input element?

javascript angular typescript

Answer 1

Answer №1

When you need to retrieve the file value of an input file, you can utilize myinput.files[0]; after a change event on the input element.

It's important to note that in modern browsers, you are unable to trigger the file dialog from script without a user action (such as a click).

According to JS:14, the File chooser dialog can only be displayed with a user activation.

If you're looking for a solution to open a file dialog using native JavaScript, check out this link: How to open a file / browse dialog using javascript?

You can attach an onChange event to the input file to capture the selected file:

var fileInput = document.getElementById('theFile');
       fileInput.addEventListener('change', function() {
        var selectedFile = document.getElementById('theFile').files[0];
        console.log(selectedFile.name);
       });

function performClick(elemId) {
       var elem = document.getElementById(elemId);
       if(elem && document.createEvent) {
          var evt = document.createEvent("MouseEvents");
          evt.initEvent("click", true, false);
          elem.dispatchEvent(evt);
       }
    }
    
   var fileInput = document.getElementById('theFile');
   fileInput.addEventListener('change', function() {
    var selectedFile = document.getElementById('theFile').files[0];
    console.log(selectedFile.name);
   });

    <a href="#" onclick="performClick('theFile');">Open file dialog</a>
    <input type="file" id="theFile" />

Answer 2

When you need to retrieve the file value of an input file, you can utilize myinput.files[0]; after a change event on the input element.

It's important to note that in modern browsers, you are unable to trigger the file dialog from script without a user action (such as a click).

According to JS:14, the File chooser dialog can only be displayed with a user activation.

If you're looking for a solution to open a file dialog using native JavaScript, check out this link: How to open a file / browse dialog using javascript?

You can attach an onChange event to the input file to capture the selected file:

var fileInput = document.getElementById('theFile');
       fileInput.addEventListener('change', function() {
        var selectedFile = document.getElementById('theFile').files[0];
        console.log(selectedFile.name);
       });

function performClick(elemId) {
       var elem = document.getElementById(elemId);
       if(elem && document.createEvent) {
          var evt = document.createEvent("MouseEvents");
          evt.initEvent("click", true, false);
          elem.dispatchEvent(evt);
       }
    }
    
   var fileInput = document.getElementById('theFile');
   fileInput.addEventListener('change', function() {
    var selectedFile = document.getElementById('theFile').files[0];
    console.log(selectedFile.name);
   });

    <a href="#" onclick="performClick('theFile');">Open file dialog</a>
    <input type="file" id="theFile" />

Tips for retrieving input values when they are not available in HTML documents

Answer №1

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