Implementing Search-as-you-type with Mithril.js

I’ve been working on a new project, the front-end of which I’m coding up in ES6 with Mithril.js (using 1.0.x now after spending the better part of a day migrating from 0.2.x).  I wanted to implement “search as you type” functionality, since I’m using Elasticsearch on the back-end for its full-text search capability.

search_box

A simple user search box

Took me a bit of trial-and-error, but I came up with this mithril component that provides a simple text field that automatically fires a callback periodically (the timing is configurable)

export let SearchInputComponent = {

    /**
     * attributes:
     * helpText - small text to display under search box
     * callback - callback to be fired when timeout/minchar conditions are met
     * minchars - min number of characters that must be present to begin searching
     * inputId  - DOM ID for input field
     * @param vnode
     */
    oninit: function(vnode) {
        vnode.attrs = vnode.attrs || {};
        // Search box caption
        vnode.attrs.helpText = vnode.attrs.helpText || "Enter search text here";
        //Callback to fire when user is done typing
        vnode.attrs.callback = vnode.attrs.callback || function(){};
        //Minimum number of characters that must be present to fire callback
        this.minchars = vnode.attrs.minchars || 3;
        this.timeout = vnode.attrs.timeout || 1e3; //default 1 second for input timeout
        this.inputId = vnode.attrs.inputId || "searchTextInput";
        this.timeref = null;
        this.err = stream(false);

        this.doneTyping = function(){
            let searchString = $('#' + this.inputId).val();
            if (this.timeref && searchString.length >= this.minchars){
                this.timeref = null;
                vnode.attrs.callback(searchString);
            }

        }.bind(this);

        this.oninput = function(event){
            if (this.timeref){
                clearTimeout(this.timeref);
            }
            this.timeref = setTimeout(this.doneTyping, this.timeout);
        }.bind(this);

    },

    view: function(vnode) {
        return m("fieldset", {class: "search-input-box"}, [
            m("input", {type: "text", class: "form-control", id: vnode.state.inputId,
                autofocus: true, "aria-describedby": "searchHelp", oninput: vnode.state.oninput,
                onblur: vnode.state.doneTyping}),
            m("small", {id:"searchHelp", class: "form-text text-muted"}, vnode.attrs.helpText)
        ]);
    }

};

Pretty basic.  In my case, I wanted to avoid firing my search callback (which makes a request to my back-end search service) until a certain number of characters had been entered.

One thought on “Implementing Search-as-you-type with Mithril.js

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