英文:
Puppeteer : how to pass argument to page evaluate?
问题
我想要传递一个参数给Puppeteer的page.evaluate方法。
我可能仍然在 struggle with async/await that I don't master,所以我的知识问题可能更一般。无论如何，Puppeteer是当前需要解决的问题。
我有这段代码来更新一个<span>元素。它工作得很好：
await page.evaluate(
() =>
(document.querySelector(
"selector"
).innerHTML = "WHATEVER")
);
"WHATEVER"的值来自外部变量。我需要将它传递给evaluate。
我尝试过：
const value = "WHATEVER"
async function setValue(val) {
console.log(val) //OK
await page.evaluate(
()=>{
console.log(val) // KO Error [ReferenceError]: val is not defined
document.querySelector(
"selector"
).innerHTML = val
}
);
}
await setValue(value) // KO
为什么val没有被定义？
在这种情况下如何传递参数给page evaluate？是否有替代方法？
英文:
I want to pass an argument to Puppeteer page evaluate method.
I might just be still struggling with async/await that I don't master,so my knowledge issue might be more general. Anyway Puppeteer is the current problem to be solved.
I have this snippet for updating a <span> element. It works well:
await page.evaluate(
() =>
(document.querySelector(
"selector"
).innerHTML = "WHATEVER")
);
"WHATEVER" value comes from an outside variable. I need to pass it along to evaluate.
I tried with :
const value = "WHATEVER"
async function setValue(val) {
console.log(val) //OK
await page.evaluate(
() =>{
console.log(val) // KO Error [ReferenceError]: val is not defined
document.querySelector(
"selector"
).innerHTML = val
}
);
}
await setValue(value) // KO
Why is val not defined?
How to pass an argument to page evaluate in this case? Is there an alternative?
答案1
得分: 1
`page.evaluate()`与Node.js环境隔离，这意味着它无法访问来自Node.js脚本范围的变量。
要将参数传递给您提供给`page.evaluate()`的函数，您应将其作为额外的参数包括在内。
实际上，这是方法签名：
page.evaluate(pageFunction, ...args);
所以你需要像这样做：
const value = "WHATEVER"
async function setValue(val) {
console.log(val) //OK
await page.evaluate(
(val) => {
console.log(val) // 现在应该是OK的
document.querySelector("selector").innerHTML = val
},
val // 这是您将参数'val'传递给page.evaluate()中的函数的地方
);
}
await setValue(value)
英文:
page.evaluate() is isolated from the Node.js environment, which means it does not have access to variables from your Node.js script scope.
To pass an argument to the function you provide to page.evaluate(), you should include it as an additional parameter.
In fact this is the method signature:
page.evaluate(pageFunction, ...args);
So u need to so something like this:
const value = "WHATEVER"
async function setValue(val) {
console.log(val) //OK
await page.evaluate(
(val) => {
console.log(val) // Should be OK now
document.querySelector("selector").innerHTML = val
},
val // This is where you're passing the argument 'val' to the function in page.evaluate()
);
}
await setValue(value)
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