[英]Using Chai expect dynamically
我正在嘗試動態生成mocha測試,但是我遇到了問題:
expect([1, 2, 3])['to']['deep']['equal']([1, 2, 3]);
然而,工作正常
var e = expect([1, 2, 3]);
e = e['to'];
e = e['deep'];
e = e['equal'];
e([1, 2, 3]);`
產生
Uncaught TypeError: this.assert is not a function at assertEqual (node_modules/chai/lib/chai/core/assertions.js:487:12) at ctx.(anonymous function) (node_modules/chai/lib/chai/utils/addMethod.js:41:25)
在e([1, 2, 3]);
。 知道這里出了什么問題,或者我將如何解決這個問題?
默認情況下,JavaScript方法不受約束。
var a = {whoAmI: 'a', method: function() {console.log(this);}}
var b = {whoAmI: 'b'};
console.log(a.method()); // will print a
var method = a.method;
method(); // will print the global object (Window)
b.method = method;
b.method(); // will print b
如果需要綁定,可以使用閉包:
// simple case
var method = function() {return a.method();}
// slightly more complex case, supporting arguments
var method = function() {return a.method.apply(a, arguments);}
method(); // will print a
b.method = method;
b.method(); // will still print a
或者您可以使用內置的.bind()
方法。
var method = a.method.bind(a);
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