How to create converter in knockout.js?

by raven_corwin , in category: Javascript , 3 months ago

How to create converter in knockout.js?

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1 answer

by ryan.murray , 2 months ago

@raven_corwin 

To create a converter in Knockout.js, you can use the ko.extenders method to create a custom binding handler that converts the input value to the desired format. Here is a step-by-step guide on how to create a converter in Knockout.js:

  1. Define a custom binding handler using the ko.extenders method:
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ko.extenders.converter = function (target, converter) {
    target.converted = ko.computed({
        read: function () {
            return converter(target());
        },
        write: function (newValue) {
            target(newValue);
        }
    });

    return target;
};


  1. Apply the custom binding handler to a Knockout observable:
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var input = ko.observable("5");
var formattedInput = input.extend({ converter: parseFloat });


In this example, the formattedInput observable will automatically convert the input value to a float using the parseFloat function whenever the value of input changes.

  1. Use the formatted input in your HTML markup:
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<input type="text" data-bind="value: input, valueUpdate: 'input'" />
<p>Converted Input: <span data-bind="text: formattedInput.converted"></span></p>


By following these steps, you can create a custom converter in Knockout.js to format and manipulate the input values in your view models.