javascript 类型错误：字符串不是函数
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TypeError: string is not a function
提问by Nate
In the following code, TypeError: string is not a functionon line 30 var myColour = new colour(255,255,255);is thrown. Can anyone see what is wrong with the code. Many thanks.
在下面的代码中，TypeError: string is not a function第 30 行var myColour = new colour(255,255,255);被抛出。任何人都可以看到代码有什么问题。非常感谢。
var bodies = [];
var orbits = [];
var colours = [
new colour(45, 45, 45),
new colour(255, 0, 0),
new colour(0, 157, 255),
new colour(77, 250, 81),
new colour(255, 247, 0)
];
function colour(red, green, blue)
{
this.red = red;
this.green = green;
this.blue = blue;
};
window.onload = function() {
var c = document.getElementById("theCanvas");
var ctx = c.getContext("2d");
ctx.beginPath();
ctx.arc(95,50,40,0,2*Math.PI);
ctx.stroke();
for (var colour in colours){
console.log(colour.red);
console.log(colour.green);
console.log(colour.blue);
};
var myColour = new colour(255,255,255);
console.log(myColour.red);
console.log(myColour.green);
console.log(myColour.blue);
};
回答by Some Guy
You have a local variable called colourin the for...inloop, and that is not a function. Change that variable to something other than the constructor function, like cand it'll work fine. Your code, corrected:
你有一个colour在for...in循环中调用的局部变量，它不是一个函数。将该变量更改为构造函数以外的其他内容，例如c，它会正常工作。您的代码，已更正：
var bodies = [];
var orbits = [];
var colours = [
new colour(45, 45, 45),
new colour(255, 0, 0),
new colour(0, 157, 255),
new colour(77, 250, 81),
new colour(255, 247, 0)
];
function colour(red, green, blue)
{
this.red = red;
this.green = green;
this.blue = blue;
};
window.onload = function() {
var c = document.getElementById("theCanvas");
var ctx = c.getContext("2d");
ctx.beginPath();
ctx.arc(95,50,40,0,2*Math.PI);
ctx.stroke();
for (var c in colours){
console.log(c.red);
console.log(c.green);
console.log(c.blue);
};
var myColour = new colour(255,255,255);
console.log(myColour.red);
console.log(myColour.green);
console.log(myColour.blue);
};?
回答by Hui Zheng
Local variable colourdefined in for (var colour in colours)will be hoistedto the beginning of the onloadfunction, so it will hide the global function colour. Changing the latter to Colourwill solve your problem. Besides, it's good convention to capitalize the name of a function which serves as a Classname.
中colour定义的局部变量for (var colour in colours)会被提升到onload函数的开头，所以会隐藏全局函数colour。将后者更改为Colour将解决您的问题。此外，将用作名称的函数的名称大写是一个很好的约定Class。
