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rated 0 times [  111] [ 2]  / answers: 1 / hits: 54007  / 9 Years ago, sun, may 10, 2015, 12:00:00

I'm working with Reactjs, writing a menu component.



use strict;

var React = require(react);
var Menus = React.createClass({

item_url: function (item,categories,articles) {
console.log('afdasfasfasdfasdf');
var url='XXX';
if (item.type == 1) {
url = item.categoryId == null ? 'javascript:void(0)' : path('buex_portal_browse_category', {slug: categories[item.categoryId].slug});
} else if (item.type == 2) {
url = item.articleId == null ? 'javascript:void(0)' : path('buex_portal_view_article', {slug: articles[item.articleId].slug, id: item.articleId});
} else {
url = item.url;
}
return url;
},

render: function () {
// console.log(this.props.menus); // return correctly
var menuElements = this.props.menus.map(function (item1) { // return fault : 'cannot read property 'props' of undefined '
return (
<div>
<li>
<a href={this.item_url(item1, this.props.categories, this.props.articles )}>{item1.name} // the same fault above
<i class=glyphicon glyphicon-chevron-right pull-right></i>
</a>
<div class=sub-menu>
<div>
{item1._children.map(function (item2) {
return (
<div>
<h4>
<a href={this.item_url(item2, this.props.categories, this.props.articles)}>{ item2.name }</a>
</h4>
<ul>
{item2._children.map(function (item3) {
return (
<div><li><a href={this.item_url(item3, this.props.categories, this.props.articles) }>{ item3.name }</a></li></div>
);
})}
</ul>
</div>
);
})}
</div>
</div>
</li>
</div>
);
});

return (
<div class=menu>
<ul class=nav nav-tabs nav-stacked>
{menuElements}
</ul>
</div>
);
}
});


Whenever I use 'this' inside map function it is undefined, but outside it is no problem.



The error:




Cannot read property 'props' of undefined




Anybody help me ! :((


More From » reactjs

 Answers
3

Array.prototype.map() takes a second argument to set what this refers to in the mapping function, so pass this as the second argument to preserve the current context:



someList.map(function(item) {
...
}, this)


Alternatively, you can use an ES6 arrow function to automatically preserve the current this context:



someList.map((item) => {
...
})

[#66656] Friday, May 8, 2015, 9 Years  [reply] [flag answer]
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raveno

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