React.js - conditionally use dangerouslySetInnerHTML

Question

I have some code to Regex some text and wrap it in a <span /> like so:

highlightQuery() {
    // will output the text response from the Model, but also highlight relevant words if they match the search query
    // that the user input
    let input = this.props.model.get('value');

    if(!this.state.hasMatch){
        return input;
    }

    let query = this.props.matched.query,
        index = this.props.model.get('searchIndexes')[this.props.matched.index];

    const replaceBetween = (str, start, end, what) => {
        return str.substring(0, start) + what + str.substring(start + end);
    };

    let ret = replaceBetween(input, index, query.length, `<span class='highlighted'>${query}</span>`);

    return ret;
},

render() {

    const classes = classNames(
        this.props.model.get('type'),
        'character'
    );

    return (
        <span key={this.props.model.cid} className={classes} dangerouslySetInnerHTML={ {__html: this.highlightQuery()} }>
            {!this.state.hasMatch && this.highlightQuery()}
        </span>
    );
}

However, this yields: Uncaught Error: Invariant Violation: Can only set one of children or props.dangerouslySetInnerHTML.

How am I best to conditionally use dangerouslySetInnerHTML?

Solution 1

You can define an element (and its properties) before calling the render function, like so:

var return = {};
if(myCondition) {
    return = <span key={this.props.model.cid} className={classes}>
                {!this.state.hasMatch && this.highlightQuery()}
             </span>
} else {
    return = <span key={this.props.model.cid} className={classes} dangerouslySetInnerHTML={ {__html: this.highlightQuery()} }></span>
}

Then you can just render the return var.

Solution 2

and make sure you do not include a space between the span tags else you would run into the following error:

invariant.js:39 Uncaught Invariant Violation: Can only set one of children or props.dangerouslySetInnerHTML.

return = <span key={this.props.model.cid} className={classes} dangerouslySetInnerHTML={ {__html: this.highlightQuery()} }>NO SPACE OR TEXT HERE</span>

Solution 3

You can use spread syntax if you are using ES2016.

const options = {};
if (useHTML) {
  options.dangerouslySetInnerHTML = {__html: yourHTML};
} else {
  options.children = [<ChildNode/>];
}
return <span {...options} className="myClassName"></span>

Comments

[Aviran]

you probably want a better name than 'return' for a variable.

[saawsann]

In my case, I had a linebreak between the opening and closing tag. It generated the following warning Only set one of children or props.dangerouslySetInnerHTML - react/no-danger-with-children.

[abettermap]

In case you want to investigate/ignore the potential eslint complaint which might show up in regards to prop spreading, here are the docs for it.