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next.js/lib/utils.js

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export function warn (message) {
if (process.env.NODE_ENV !== 'production') {
console.error(message)
}
}
export function execOnce (fn) {
let used = false
return (...args) => {
if (!used) {
used = true
fn.apply(this, args)
}
}
}
export function deprecated (fn, message) {
// else is used here so that webpack/uglify will remove the code block depending on the build environment
if (process.env.NODE_ENV === 'production') {
return fn
} else {
let warned = false
const newFn = function (...args) {
if (!warned) {
warned = true
console.error(message)
}
return fn.apply(this, args)
}
// copy all properties
Object.assign(newFn, fn)
return newFn
}
}
export function printAndExit (message, code = 1) {
if (code === 0) {
console.log(message)
} else {
console.error(message)
}
process.exit(code)
}
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export function getDisplayName (Component) {
if (typeof Component === 'string') {
return Component
}
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return Component.displayName || Component.name || 'Unknown'
}
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export function isResSent (res) {
return res.finished || res.headersSent
}
export async function loadGetInitialProps (Component, ctx) {
if (process.env.NODE_ENV !== 'production') {
if (Component.prototype && Component.prototype.getInitialProps) {
const compName = getDisplayName(Component)
const message = `"${compName}.getInitialProps()" is defined as an instance method - visit https://err.sh/next.js/get-inital-props-as-an-instance-method for more information.`
throw new Error(message)
}
}
if (!Component.getInitialProps) return {}
const props = await Component.getInitialProps(ctx)
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if (ctx.res && isResSent(ctx.res)) {
return props
}
if (!props) {
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const compName = getDisplayName(Component)
const message = `"${compName}.getInitialProps()" should resolve to an object. But found "${props}" instead.`
throw new Error(message)
}
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return props
}
export function getLocationOrigin () {
const { protocol, hostname, port } = window.location
return `${protocol}//${hostname}${port ? ':' + port : ''}`
}
export function getURL () {
const { href } = window.location
const origin = getLocationOrigin()
return href.substring(origin.length)
}